US Navy Construction Battalions (Seabees) In France and Germany During World War Two.
|Planning for the Invasion|
|Organizing for the Invasion
Plans for the invasion of Normandy began to take shape by the summer of 1943. Decisions of controlling importance were made in August, when the political and military leaders of the United States and Great Britain conferred in Quebec.
The role of the naval forces was to be primarily that of assuring a successful landing on the French coast, providing the shore facilities necessary to permit the uninterrupted delivery of great numbers of troops and vast quantities of material, and the maintenance of an open supply route across the English Channel.
Participation in the invasion by American naval forces was obviously going to require extensive logistic support. A supply depot, large enough to store and issue great quantities of naval supplies of all kinds, would be needed, and a number of shore bases to support the forthcoming amphibious operations would have to be provided.
In the summer of 1943 the task of building the Navy's base facilities in Northern Ireland and Scotland had been virtually accomplished. Only minor construction remained to be done, and thereafter the problems would be those of maintenance and operation. At the same time, a large new program of base construction in southern England loomed ahead.
In view of these circumstances the 29th Construction Battalion, which had been engaged since the previous November in building the Londonderry and Rosneath bases, was moved to Devon and Cornwall, and the Seabee personnel in the United Kingdom was augmented by the 81st and 97th Construction Battalions and the second section of the 10th Special Battalion. The 97th took over the base operation and maintenance work in Northern Ireland and Scotland, from the 29th, the first section at Londonderry and the second at Rosneath. The second section of the 10th Special was also assigned to duty at Rosneath. The 81st Construction Battalion was dispatched to Milford Haven, Wales, to begin construction of new facilities.
On September 24, 1943 the construction battalions in the United Kingdom were organized into the 13th Naval Construction Regiment, so as to provide an overall command and maximum flexibility of personnel and equipment in connection with construction operations in the area. The regiment was designated as part of the organization of the Commander of Landing Craft and bases in Europe.
By November, all the Seabee units in the United Kingdom, with the exception of the first section of the 97th Battalion, were at work on the new bases in Devon, Cornwall, and Wales. In December, they were joined by the 1006th Construction Battalion Detachment, which had performed pontoon-causeway work with distinction in the Sicilian and Italian invasions.
The largest single base-construction project undertaken by the Seabees in southern England was the supply base near Exeter, in Devon. On what had been the golf course of a country club, south of the city, the 29th Battalion set up its headquarters, and on October 11, 1943, broke ground for the new depot.
Originally, the plan for the station called for the erection of 79 warehouses, to provide about 40,000 square feet of covered-storage space, personnel facilities for 1,000 men, and the necessary administration buildings. After construction was well under way, in December, the plans for the base were changed to provide a much larger capacity than had been originally intended. A total of 578,000 square feet of covered storage was finally attained. Most of the storage buildings were of the quonset-hut type, 40 by 100 feet; a number of buildings of British design were also put up. Standard-size quonset huts were used for personnel quarters and office facilities. About 7 miles of roadway were built to serve the base.
The depot was commissioned on February 4, 1944.
The principal locations chosen for the amphibious
Bases in Southern England and in Normandy
bases were Falmouth, Fowey, Plymouth, Salcombe, Dartmouth, and Teignmouth, on the Channel coast, and Milford Haven and Penarth in Wales. In addition, installations of smaller magnitude were provided at St. Mawes (across the harbor from Falmouth), Saltash, Calstock, Weymouth, Poole, Southampton, and Instow (on the Bristol Channel).
There were fully developed port facilities already existing at all those places, and many of them had also been used for many years as British seaside resorts. Consequently, much of the problem of housing naval personnel could be met by utilizing existing hotel facilities and large private homes, with appropriate alterations. As practically all the British Channel coast was designated as a restricted area during the months preceding the invasion, and civilian travel into the area prohibited for reasons of military security, the utilization of existing civilian facilities in that way presented no particular hardship to the British people. Additional capacity for housing naval personnel was found in some existing British army camps, which were turned over to the Navy for that purpose.
After the maximum feasible use had been made of such existing facilities, however, it was still necessary to provide new housing at several locations. At some places, new personnel quarters were provided by the erection of quonset huts, or roughly equivalent huts of a British design; at others, by the erection of tents; and at still others, all those forms of housing were used. The capacity for housing naval personnel provided at each of those locations was as shown in Table VI.
To obtain proper dispersal, in view of the constant hazard of enemy bombing, concentration of more than a thousand men at any one point was avoided whenever possible. Thus, at Plymouth, where far more than a thousand men needed to be housed in the general area, several hut camps were erected, each at some distance from the waterfront hotels and well separated from each other. Similar conditions prevailed at Falmouth.
The building of these advanced amphibious bases was put underway at various times beginning in October 1943. By January 1944, the construction of most of them had reached the stage where occupancy could begin.
Similarly, for the hospital and dispensary facilities necessary to serve the large number of men to be assembled for training and participation in the assault, existing hotels or large homes were taken over by the American forces, and suitable alterations were made to fit them to hospital purposes. Where the available buildings were not adequate, they were supplemented by the erection of quonset-hut annexes.
Naval Construction Battalion Depot, Heathfield
Open storage area, left and upper left; large single quonset hut, transportation department's garage; small huts, offices and personnel quarters; two double huts (right foreground), messhall and recreation huts; tents used for temporarily housing transient Seabees.
The largest single installation was at Netley, just
outside Southampton, where an old British hospital
was remodeled to provide a 3000-bed facility.
Two major hospitals were provided entirely of
quonset huts--one at Manadon Field, on the outskirts
of Plymouth, with a capacity of 500 beds;
the other, at Milford Haven, with a capacity of
200 beds. In addition, a large home in Falmouth
was converted into a 140-bed hospital.
For ship repair and servicing facilities, little new construction was necessary, as the southern coast of England was already well provided with such facilities. Such work as had to be done consisted principally of installing additional machinery in existing shops, providing a few small marine railways and "hards," and the erection of a limited number of storage sheds.
In March 1944, authority was received for the establishment of a Seabee base of operations, at Heathfield, near Newton Abbot, in Devon. The 81st Battalion worked on the new camp for about a month, as a "fill-in" job, directing its attention principally to the roads and camp utilities. The project was turned over to the 29th Battalion in the latter part of April. When completed, the camp provided for about a thousand men, one-third in
quonset huts and the remainder in tents, together with storage and repair facilities for construction and transportation equipment.
The Bay of the Seine, where the invasion was to take place, is characterized by flat sandy beaches, with an average slope of 1 to 150 feet, and an average range of 21 feet between high and low tides. The duration of high water is about 3 hours. A tidal current runs parallel to the coast, at about 3 knots. A series of low sand-bars, also parallel to the beach, exists in the tidal area, with the runnels between them attaining a depth of as much as 5 feet.
The plan adopted to meet this difficult problem was bold. It was decided to prefabricate in England the breakwaters and other port facilities that would be needed to create the necessary artificial harbors on the Normandy coast, to tow them across the English Channel with the invading forces, and to install them at the chosen locations at the time of the assault.
This decision was reached at the Quebec conference in August 1943. The details of the plan were developed under the auspices of the Combined Chiefs of Staff during the months that followed.
Assaults were to be made by American forces at two points on the Normandy coast, one on the
Interior of Temporary Ward, St.Michael's Hospital, Falmouth
eastern side of the Cherbourg peninsula, northwest of Carentan, at the village of St.Martin de Varreville, and the other some 20 miles farther east, where the coast line runs more nearly east and west, at St.Laurent sur Mer. During the planning of the invasion, these two locations were given the code designations of "Utah" and "Omaha," respectively, and those designation have subsequently come into use as geographic names. Beaches to be assaulted by the British forces were to be east of the American locations, at Arromanches, at Courseulles, and at Ouistreham.
Logistically, Omaha was planned to be the major American location, with Utah fulfilling a supporting and supplementing function. At both beaches there were to be "gooseberries," harbors of refuge for small landing-craft, but for Omaha a great artificial harbor, called a "mulberry," was planned to give a protected anchorage about two square miles in extent, to be provided with moorings for seven Liberty ships, five large coasters, and seven medium coasters. This harbor was to be adequate to handle 5000 tons of stores per day, plus such military vehicles as would be delivered.
For the British beaches, an installation similar to that for Omaha, but somewhat larger, was planned at Arromanches; at their other two beaches, gooseberries only were to be provided.
It was clear from the beginning that the mulberry problem consisted essentially of two parts. First, the protected anchorage could be effected only by means of some sort of breakwater. Second, some way would have to be found to bridge the gap between the ship at anchor and the "dry land" beach, so that supplies and vehicles could go ashore with no delay.
Uneven Omaha Beach
Pontoon causeway is 28 feet wide
Five methods of constructing the necessary
breakwater were studied with great care. They
were (1) Lilo floating breakwaters, (2) bubble
breakwaters, (3) floating ships, (4) blockships,
and (5) concrete caissons. Analysis and tests on
models led to the elimination of the first three
methods. The choice fell on the blockship and the
concrete-caisson methods, and it was decided to
employ both--blockships to form the harbors of
refuge for small craft, and concrete caissons to
form the primary breakwater and provide sheltered
anchorage for cargo ships.
Some means had to be provided to take ashore the cargo unloaded from the ships in the harbor formed by the breakwater. From Liberty ships and smaller cargo vessels, vehicles and supplies could be lightered to the beach by LCT's [Landing Craft, Tank] or other ferry craft. The normal method of unloading LST's [Landing Ship, Tank], however--beaching and discharging vehicles under their own power, over a bow ramp--appeared to be precluded by the extremely flat beach and the great tidal range. The LST would run aground at the stern, too far out from shore, in water about 4 feet deep at the bow, and a receding tide would leave the ship stranded on an uneven beach for a long time, causing serious delays in maintaining the flow of supplies and probably introducing excessive hogging stresses in the vessel. LCT's could be used as lighters to serve the LST's, but there would not be enough of these smaller landing-craft available to handle the great number of vehicles that would have to pass over the beaches each day.
Five methods of bridging the gap between ship and shore were given consideration: (1) spud pier-heads and flexible piers, sponsored by the Director of Transportation of the British War Office, (2) Swiss roll, (3) U.S. Navy lighter pontoons, (4) pontoons as developed by the British Director of Transportation, and (5) Hughes piers. At an early date it was decided to use the spud pier-heads and flexible piers to provide the physical connection between ships and shore, and rhino ferries [42-by-176 foot flat-bottomed pontoon barges], constructed of the U.S. Navy lighter pontoons, to transport vehicles and supplies from moored vessels to the beach. The Swiss roll, the Director of Transportation's pontoons, and the
Hughes pier were judged impractical to meet the requirements.
The plan called for the installation by D-plus-2 of those "port" facilities that would provide the small-craft harbors of refuge at both Utah and Omaha. Those harbors were to be formed by scuttling a number of merchant ships, bow to stern, roughly parallel to the shore, in about two fathoms of water, in the lee of which small craft, such as barges, LCI's [Landing Craft, Infantry], and LCT's, protected from the force of the sea, could discharge personnel and equipment needed immediately to support the beach assault. Each line of sunken ships was known as a "gooseberry."
Gooseberry One, to be installed at Utah, was to consist of ten ships which, when sunk end to end, would form a breakwater about 4000 feet long and 4500 feet offshore at high tide.
At Omaha, Gooseberry Two was to consist of fourteen merchant ships, an old British warship, the former battleship Centurion, heading the western end of the line. The length of the gooseberry at Omaha would be about 6500 feet, and it would lie 4000 feet offshore at high tide.
In all instances the ships, without cargo, manned by Merchant Marine crews, would accompany the invasion forces, and after being sited in their proper locations by tugs would be sunk by setting off explosive charges which would blow out their bottoms.
The artificial harbor for Omaha was to be formed by a breakwater installed just west of the gooseberry. It was to be composed of a series of open concrete-caissons, which would be towed cross the Channel, sited in their planned locations, flooded, and sunk. Each caisson was known as a phoenix.
The design of the harbor called for an outer breakwater, 6500 feet long, parallel to the beach, 4500 feet offshore at high tide, at about the 5-fathom line, and a western arm, 1600 feet long, extending to the beach. Between the Centurion, heading the gooseberry, and the eastern end of the outer breakwater, a 600-foot opening was to be left to serve as a harbor entrance. Another entrance was to be provided by an opening, 200 feet wide, roughly in the center of the outer breakwater. A space, 600 feet wide, separating the outer breakwater from the offshore end of the western breakwater arm, would provide a third entrance to the protected area.
About 2400 feet offshore from the phoenix breakwater, to reduce swells and waves and to provide some measure of protection for large ships
LST Moves in to Secure to a Leibnitz Pier, Omaha Beach
Phoenixes at Omaha Beach
Note anti-aircraft guns and blimps
which would have to anchor outside the mulberry proper, was to be placed a floating breakwater about 6000 feet long. It was to consist of a series of 24 individually moored steel floats, 200 feet long, called "bombardons." The floats were to be of cruciform cross-section, with the arms of the cross 10 feet long and 5 feet wide. The overall height of the float, like its overall width, would be 25 feet, and it would be so ballasted as to float with a 6-foot freeboard.
The spud pier-heads, sponsored by the Director of Transportation of the British War Office, had been designed and manufactured prior to the inception of the plan to build the mulberries, by a private firm in the United Kingdom, and several had been placed in operation in the vicinity of Cairnhead, Scotland, for unloading supplies from ships. They were composed of floating steel barges, 200 feet long, 60 feet wide, and 10 feet deep. Six of these pier-heads were to be provided for installation behind the breakwater at Omaha. They were to be placed far enough out from shore to provide a draft of not less than 9 feet at lowest low-tide; they were to be placed adjacent to each other and so connected by ramps and bridges that they could function together as an articulated structure in the cargo-unloading operation. At several of the pier-heads, LST's could tie up, lower their ramp, and discharge their cargoes of vehicles. Coasters were to unload at the others.
Access to the shore, 3100 feet away at high tide, was to be provided by three multi-span bridges, roughly 500 feet apart. Each bridge would consist of a series of 80-foot steel-truss spans, supported at the ends by moored concrete or steel floats. The western bridge was to be strong enough to pass loads up to 40 tons; the other two were to be capable of handling 25-ton loads. The bridge installation became known as a "whale," and the supporting floats were known as "beetles."
To aid in getting materials ashore in a hurry, particularly military vehicles, from Liberty ships, coasters, and LST's, the rhino ferry was conceived. In view of the limited number of LCT's that could be made available to serve as ferry craft, the
Bombardons Moored in Position off Omaha Beach
These floating breakwaters were used for the protection of ships anchored outside the mulberry
Bureau of Yards and Docks was requested to develop a ferry barge composed of pontoons, which could be towed at sea by an LST, and by which an LST could be completely unloaded in two trips. A barge having a capacity of 300 tons, six pontoon strings wide and 30 pontoons long, was made up and tested in August 1943, at the Advance Base Proving Ground at Davisville, R.I. Its performance was observed by a committee composed of representatives of the Staff Commander of the 6th Amphibious Force, the British Admiralty Delegation, the Bureau of Yards and Docks, and the Proving Ground itself. On the basis of tests the tentative design was accepted, with the understanding that further development of the equipment and of the operating technique would be undertaken in the United Kingdom.
It was planned that the rhino, when teamed with an LST, would be made fast, or "married," to the landing ship, stern to bow; vehicles would be able to transfer from the LST to the ferry and leave the ferry at the beach under their own power. When ashore, the ferry would discharge at one of the sunken causeways or, if necessary, discharge its cargo directly onto the beach.
Twenty such rhinos would be needed at Omaha, it was decided, and eleven at Utah.
It was apparent that some means would have to be provided to enable ferry craft coming ashore in the lee of the gooseberries to discharge their cargoes and to retract quickly from the beaches. The invasion plan could not afford the time that would be lost if the craft should be beached and then stranded by a falling tide. Moreover, reconnaissance reports indicated that patches of clay and mud would probably be encountered on portions of the beaches between high and low water and, therefore, that hardways of some sort would be required if vehicles were to move across the tidal area without hazard of miring.
Staff engineers at Allied Supreme Headquarters concluded that Navy lighter pontoons, formed into sunken causeways, presented the only practicable solution using known and tried equipment. It was recommended that the causeways should be installed on the beaches on D-Day or as soon thereafter
Rhino Ferries in Action at Omaha Beach
Loaded rhino coming in to the beach; emptied rhino (foreground) being repaired on return trip.
after as feasible. Analysis of the expected ferry movements led to the conclusion that causeways would have to handle one-half of the total daily ferry cargo discharged. Taking into account the number of beach exits required, led to the conclusion that four causeways would be needed at the American beaches--two at Omaha and two at Utah--and six at the British beaches.
Made up of the Navy's standard steel pontoons, the causeways were to be two strings, or about 14 feet, wide, and were to extend from the high-water line out to somewhat beyond the line of minimum low-water, a distance of 2450 feet. Flooded and resting on the sand, these causeways would provide a hard roadway to which barges and landing-craft could tie at any stage of the tide, and over which their personnel or vehicles could go ashore in the dry. To facilitate the berthing of these craft, each causeway was to be equipped with eight "blisters," or sunken stages roughly equivalent to pier-heads, staggered on alternate sides, four pontoons wide and twelve long, spaced 250 feet apart.
The provision of the outboard engines was one of the modifications made in the rhino design as a consequence of operating tests made in English waters. The Olson ramp was another, replacing a 60-ton-capacity ramp called for in the original design accepted tentatively at Davisville. Other changes included the addition of plastic-armor shields for the coxswains, the elimination of a hinged fair-lead, and the adoption of a closed cooling-system for the outboard engines.
Assembly of the rhino ferries was begun at Falmouth in late November 1943, by a detachment from the 81st Seabees. While the first unit was
being fabricated, a search had been made for other
sites along the south coast of England suitable for
rhino assembly, and satisfactory sites were found
at Plymouth and Dartmouth. The 1006th Detachment
arrived from the Mediterranean theater of
operations in December and took over the assembly
work at Falmouth and the setting up of the
new assembly areas at Plymouth and Dartmouth.
By the end of January 1944, rhino assembly was
under way at all three locations. The 1006th Detachment
manned the assembly yards until March,
when the 111th Battalion took over the task.
The Plymouth yard continued to build rhinos until early in May, but the yards at Falmouth and Dartmouth turned to the assembly of the causeways as soon as their assigned quotas of rhino ferries had been completed.
For the sunken causeways, 28 pontoon strings, each two pontoons wide and thirty long, were assembled, together with 16 causeway "blisters."
Each causeway string was 176 feet long, a convenient length to tow.
In addition, the Seabees fashioned out of the pontoons, 36 rhino tugs, intended to provide the auxiliary motive power for the rhino ferries; 12 causeway tugs, to assist LCT's in berthing and unberthing at the causeways; 12 warping tugs, designed primarily to pull broached boats off the beach; 2 rhino repair barges, almost as large as the rhino ferries, each fitted with two 5-ton cranes and a toll house; and 2 floating drydocks, of 475-ton capacity, enough to dock an LCT.
The Phoenixes.--For installation at Omaha, 51 phoenixes of six different sizes were built by the British in a number of drydocks and in tidal basins excavated especially for the purpose, mostly in the Thames estuary.
The cross-section adopted for the largest caissons, for the outer breakwater, had the shape of an inverted T, 60 feet high. For the first 28 feet of its height, the width was 56 feet 3 inches; for the remainder of its height, 44 feet 1 inch. A set-back, or working platform, on each side, 6 feet 1 inch wide, was formed thereby. When afloat, the phoenix had a draft of 20 feet 3 inches, giving a freeboard of 7 feet 9 inches to the set-back. When sunk in five fathoms of water the freeboard of the breakwater-unit was 30 feet at low tide, and 9 feet at high tide.
Outer walls were 14 inches thick, and the floor thickness was 15 inches, over a portion of which concrete ballast was placed 15 inches thick. A center wall, 9 inches thick, extended throughout the phoenix's length; ten cross walls, of the same
Personnel Huts at Vicarage Base, Plymouth
Naval Dispensary, Manadon Field, Plymouth
thickness, 16 feet 6 inches apart in the clear, divided the interior of the caisson into 22 cells. In each caisson's outer walls, five sets of 12-inch valves were installed, to serve as sea cocks. Near the bottom of the first, third, fifth, sixth, and eighth cross-walls, 12-inch-square holes were left, so that in the sinking operation the phoenix contained ten separate compartments to be flooded. Large openings, 16 feet high, were left in both the longitudinal and the cross walls, with their sills 34 feet 9 inches, above the phoenix's floor.
At each end of the phoenix the space between the end wall and the first cross-wall was decked over with a reinforced-concrete slab, and, forward, an intermediate deck was provided in the space thus formed, and fitted out as quarters for the riding crew. Just aft of the midship point a gun platform was constructed, mounting a 40-mm. Bofors.
The design and construction of the phoenixes was a commitment by the British; the actual design was made by the Director of Ports and Inland Water Transportation of the War Office, with the assistance of several civilian designing engineers. The Ministry of Supply was responsible for the construction of the units, under civilian contracts, and for the inspection of construction.
Preliminary designs were sent to Washington to the Bureau of Yards and Docks in late October 1943, for checking. The analysis in Washington led to the view that the design was inherently weak in view of the conditions likely to be encountered, and an alternate design was proposed, with straight sides and capable of being ballasted with sand for the phoenix's entire height. When these views
were brought to the attention of the British designing
engineers, they differed with the conclusions,
making the point that the breakwater was
to be used for no more than a few summer months.
In the ensuing discussions the Deputy Chief Engineer of the U.S. Army Forces in the European theater participated, and, unsatisfied that the British design would meet all the situation's requirements as to strength and stability, called in a consulting engineer to make a complete examination of the problem. The consulting engineer, Dr. Oscar Faber, reported that in his opinion there were certain defects in the design and made specific recommendations for correcting weaknesses. The recommendations, in general, were directed toward increasing the thicknesses of the interior walls and the amount of reinforcement used. Although the British designing engineers thereupon increased to some extent the amount of reinforcing steel to be placed in the walls, they were firm in their view that the wall thicknesses were adequate.
No further objections were raised by U.S. Forces to constructing the phoenixes as designed.
The Pier-Heads--Six floating pier-heads for Omaha were manufactured by the British at Cairnhead, Scotland. As has been stated, each pier-head consisted of a steel barge, 200 feet long and 60 feet wide. It was designed to be partially supported by "spuds," or legs, 89 feet long, at the corners, which would extend above the platform. These spuds were built-up steel columns, 48 inches square. Although they were to rest upon the channel floor, they were not intended to support the pier-head's entire weight but, rather, to carry just enough load to anchor and steady it, with buoyance supporting the rest. Accordingly, the pier-head proper was suspended from the tops of the spuds, by an arrangement of sheaves and cables. By means of power-driven winches, it could be raised and lowered as the tide flooded and ebbed so that the amount of load carried by the spuds would remain constant. Raising and lowering operations could be carefully controlled through the use of extensometers, attached to the suspending cables.
The Floating Bridges.--Nearly two miles of "whale" bridge spans were manufactured by the British for the Omaha installation. Each standard span consisted of an 80-foot-long half-through steel truss, designed to be supported on steel or concrete
Storage Warehouses at Exeter Supply Base
floats. The trusses were lozenge-shaped, with a
maximum depth of 8 feet and were fabricated of
common structural shapes, with bolted or riveted
connections. The width of the bridge was 13 feet
9 inches center to center of trusses, and it carried
a steel deck roadway of 10 feet clear width. The
only difference between the 4-ton and the 25-ton
capacity bridges lay in the weight of the members
used to form the trusses. In addition to these
standard units, shore-ramp floats of shallow draft
were provided to fit the conditions to be encountered
at the beach end of the bridges.
Bridge spans and supporting floats were assembled into six-span trains for the tow across the Channel.
Assignment of responsibilities.--The production of the phoenixes, the pier-heads, the "whale" bridge units, and the bombardons was a commitment of the British, as was the transportation in tow from the points of manufacture to the marshalling areas from which they were to be dispatched to the Normandy coast.
The production of the rhino ferries, the sunken causeways, and all other craft to be built of pontoon gear, the manning of those units while in tow across the English Channel, and their installation and operation at the invasion beaches was the responsibility of the Seabees. In addition, the Seabees were assigned the task of manning the phoenixes, pier-heads, and "whale" bridge trains while in tow across the Channel, their installation at Omaha, and their operation and maintenance after construction had been completed.
Unloading ships in the harbor, operating harbor
Rhino Ferry "Married" to an LST
Gooseberry No. 2 at Omaha Beach
tugs, Dukw's [2 1/2 ton, 6 foot by 6 foot, amphibious truck], and providing transportation facilities ashore, from the beaches to the fighting fronts, were responsibilities of the Army.
The magnitude of the role assigned the Navy Construction Battalions in the forthcoming invasion called for an expansion of Seabee personnel and an elaboration of organization. Accordingly, effective April 1, 1944, a new naval construction regiment was formed, the 25th, with its principal function that of participating directly in "Far Shore" activities. It was composed of the 81st, 111th, 108th (a new designation for Section 2 of the 97th), and the 1006th Detachment, all from the 13th Regiment; the 28th, which was a new arrival in the United Kingdom; the 146th, a battalion specializing in P.O.L. work (Petrol-Oil-Lubricants), and the 1048th Detachment, which, newly arrived in England, was made a part of the 111th Battalion. The new regiment was charged with the planning, training for, and execution of, all projects in which Seabees would be involved in far-shore activities; the role of the 13th NCR was defined as the construction and maintenance of public works in the United Kingdom, and all pontoon construction.
The battalions of the 25th Regiment were given the following assignments for far-shore operations:
- 28th--Rehabilitation of captured ports.
81st--Manning the rhino ferries despatched to Utah while in tow across the Channel; operation of rhino ferries and beach camp at Utah.
108th--Manning the phoenixes, pier-heads, and "whale" bridge trains while in tow across the Channel; installing, operating, and maintaining them upon arrival at Omaha.
111th--Manning the rhino ferries despatched to Omaha while in tow across the Channel; operation of rhino ferries and beach camp at Omaha.
146th--Installation of P.O.L. facilities at Omaha, Cherbourg, and other captured ports.
1006th--Installation and maintenance of sunken pontoon causeways at Omaha and Utah.
As soon as the first rhino ferry was completed at Falmouth, in December 1943, two operating
Unloading Activities at Omaha Beach Mulberry
Photograph on opposite page shows another angle of this scene at a Liebnitz pier
crews were drawn from the 1006th Detachment and trained in handling the big barge. Performance tests carried out by these crews led to the modifications in rhino design noted in an earlier paragraph.
When the 111th Battalion arrived in England in February 1944, it was assigned to rhino-ferry operation, and a large-scale program of crew training was then set up. Training subjects included seamanship, signalling, aircraft recognition, marrying rhinos to LST's, beaching and retracting, and, in general, in the characteristics of rhino-ferry operation. By April 24, 1944, thirty crews from the 111th had been trained. Crews from the 28th and the 81st Battalions and the 1048th Detachment then reported for duty at Falmouth and were given a similar course of training. Rhino-ferry training was given to 41 crews in all, including 60 officers.
The crews that were to ride the mulberry units across the English Channel were drawn from the 108th Battalion. Phoenix crews were sent to the Thames estuary and rode the units that were built in that area, off Selsey Bill. When the phoenixes arrived, they had to be flooded so that they could be parked while awaiting D-day, and the parking operation served as excellent training for the siting teams. Training in the handling and assembly of whale equipment was carried on at Cairnhead, Scotland.
Spud Pierhead and Flexible Piers
For detailed view of the piers, see page 113
for Omaha, at Portland; rhinos for Utah, at Dartmouth.
On June 1, information was received that June 5 had been designated as D-day.
On June 4, information was received that D-day had been postponed to June 6.
On June 5, D-minus-1, the rhino ferries and rhino tugs, with their Seabee crews aboard, were taken in tow by LST's and left for the far shore. The invasion was under way. At 0530 the following morning, June 6, D-Day, H-minus-1, the first rhino-LST teams began to arrive at the Omaha assembly point, 12 miles offshore. Upon arrival, they were released from tow and were ordered to marry their LST's according to plan.
The sea was not running according to plan, however, for the waves were 6 feet high, and it had been thought that a 3-foot sea would be the maximum that would permit a successful rhino-LST marriage. The circumstances were extremely severe, but the marriages were successfully made, even though in the first effort most of the rhinos lost the special knee-braces with which they had been provided. The vehicles carried by the LST's moved to the rhino decks, and the ferries started for the beach, 12 miles away, between 0700 and 0800.
Upon arrival at the beach, all the rhinos were ordered to stand out, for beach obstructions had not been cleared. When the order was received
Omaha Beach Before the Mulberry Was Installed
Ships unloading on the beach while barrage balloons hover overhead
however, one rhino had already landed between
two beach obstacles and was in such a position that
it could not be retracted until mines that were
astern had been removed. Accordingly, it unloaded
on the beach at H-plus-6. All other rhinos retracted
from the beach.
They were held off until the afternoon of the next day, June 7. The sea was heavy, and the current strong; the Seabee crews, on the open deck of a barge having a freeboard of only 18 inches, had absolutely no protection from wind, weather, or enemy action. When finally ordered to the beach the rhinos had to labor for hours to get back into their proper areas.
The rhino tugs were knocked out by mines and collided heavily with submerged abandoned vehicles which began to accumulate as the assault proceeded. Most of the tugs had to be abandoned, and the rhino ferries thereafter were propelled solely by their own outboard engines.
Meantime, rhinos in tow from LST's arrived at 0300 D-day, off Utah, where the sea was at least as heavy as it was at Omaha and where bombing and strafing by German planes added to the severity of operating conditions. Nevertheless, five rhinos succeeded in marrying their LST's and in making the transfer of the vehicle load. The first rhino beached at 1400, and before midnight, four had succeeded in unloading their cargoes including landing 175 vehicles on the beach. Attacks by enemy planes were frequent, and the fire from German 88's was heavy. Rhino tugs had been
severely battered during the tow across the Channel, and the rhino ferries either made the trip from their LST's to the beach under their own power or in tow from LCT's or LCI's. At about noon on June 7, the first blockships began to arrive off Omaha and Utah. Surveys for the location had been completed an hour or so earlier, and buoys had been placed to mark the sites at which the ships were to be sunk.
By 2030 that evening, three ships had been sited and sunk in proper position at Omaha. A few minutes after the third ship had been sunk a German 88-mm. battery opened fire on the installation, and the crew was evacuated until the enemy battery had been silenced by naval gunfire. But the installation of the gooseberry had been started. Five more blockships were sited and sunk the following day, June 8, three on June 9, including the Centurion, and on June 10, D-plus-4, the Omaha gooseberry was completed by the sinking of the last three ships.
At Utah, the blockships put in their appearance at 1400 on June 7, but at that time the beach area was still under fire from the naval bombardment force and from enemy shore batteries. Although the same severe conditions prevailed throughout the next day, two blockships were successfully sited and sunk. A third ship was sited that day, but, in sinking, it drifted out of position by the stern, because of the difficulties experienced by the tugs in maintaining their positions under the severe enemy shelling. On June 9, efforts to site the fourth ship were prevented for most of the day by fire from the enemy's shore positions; however, at 1700, although still under fire, it was moved into position, and by 2030 its sinking had been completed. The fifth ship was successfully sunk just before midnight. On June 10, two more ships were placed without difficulty, but just as a third was starting for its place in the gooseberry line the site it was to occupy was bracketed by German artillery fire. The ship was brought in, nevertheless, and run aground beside a ship already in place; at high tide, two hours later, it floated off and was towed to its proper position and sunk. The siting and sinking of two more ships on June 11, D-plus-5, completed the gooseberrg at Utah. Enemy fire continued to the end, and the installation of the last
An Army DUKW Crosses One of the British-Built "Whale" Barges at Omaha Beach
ship had to be carried on under bombardment. Virtually the entire operation of constructing the Utah blockship-breakwater was carried out in the face of determined enemy opposition.
While the first ships were being sunk to form the gooseberries at Omaha and Utah, the sunken pontoon-causeway equipment began to arrive. On June 7, D-plus-1, the pontoon strings necessary to construct one causeway at each beach, together with the necessary personnel from the 1006th Detachment, arrived.
At Utah the first causeway was laid on the extreme western flank of the beach, according to plan, the next day, and it was in operation on June 8, D-plus-2. Shell fire from the same batteries that were harassing the installation of the Utah gooseberry sought out the causeway group intermittently, but caused no casualties. The second causeway arrived from England on June 14, and the next day was put into place about half a mile farther east.
At Omaha, the actual configuration of the beach was such that the feasibility of the causeway designed on the basis of intelligence reports was thrown into question. Although a section of the first causeway was laid on D-plus-3, a decision was not reached as to the best design to use, thereby permitting the full installation to go ahead, until D-plus-4, June 10. It was finally decided to make the structure four pontoons wide, instead of two as originally planned, to place the "blisters" opposite each other instead of staggering them, and to make the length 1450 feet instead of the 2450 feet originally intended. This would permit LCT's and rhinos to come to the causeway on either side; by making their approach at a 45-degree angle, they could come in at any point along its length. The second causeway at Omaha, installed on June 13, D-plus-7, was also four pontoons wide, and was in full operation June 16.
The causeways were highly successful from the very start. They were immediately put to use by all types of craft up to the size of LCI's. Within the first few hours following the installation of the first causeway at Utah, several thousand troops had gone ashore over it "in the dry."
Phoenixes for the mulberry breakwater were scheduled to arrive at Omaha in the early morning of June 8, D-plus-2. The first tows of the great concrete structures arrived, however, eight hours ahead of schedule, at 2200 on June 7. The survey for the mulberry had been begun earlier that day. The phoenixes were maneuvered into position in the western breakwater arm the next morning, flooded, and sunk. On June 9 the western arm was extended by one more unit, and a beginning was made on the outer breakwater, by the installation of its first phoenix. By that time the survey work for the mulberry had been completed, and it was possible the next day to install five more units. During the days that followed, phoenixes arrived in tow, were sited, and were sunk with considerable regularity. By June 15, the western half of the outer breakwater was complete, and only two units remained to be installed in the mulberry's western arm.
Moorings for the bombardons had been laid, starting on June 7. Installation of the floating breakwater was begun on June 8 and progressed without serious difficulty until its completion on June 13.
Survey of the site of the floating pier-heads and whale bridges had been attempted on June 7 but had had to be deferred because of the presence of many underwater obstacles and mines in the proposed location. The next day the vicinity was still under enemy sniper fire, and consequently the survey work did not get under way until June 9. Although good progress was then made, mines and underwater obstacles still prevented the start of installation until June 11, when both the western and the center bridges were begun.
The survey had indicated that the depth of water close to shore was greater than had been shown on the charts from which the mulberry operation had been planned. To take advantage of the situation, and to compensate for the loss of one bridge train while in tow across the channel, the length of all bridges was shortened 480 feet. By June 15 the center pier-head and bridge were complete, and the next morning LST's began unloading over them. Observation of unloading operations at the partly completed installation that day showed that LST's could discharge their vehicles in an average time of 64 minutes, or at the rate of 1.16 minutes per vehicle. By June 18 the western pier-head and bridge with a capacity of 40 tons, was also ready to be put into service. At that point, disaster struck the beaches.
Omaha Beach After the Great Storm
Ships, boats, and pontoons in a jumbled mass
and direction for the season. Unfortunately, it
came at a time when the eastern half of the harbor
was still unprotected.
Early in the day it was necessary to evacuate the U.S. Army anti-aircraft gun crews from several phoenixes in the outer breakwater, for heavy seas were breaking over it, sweeping away hand rails and shelters at the base of gun platforms. Before the day came to an end the outer breakwater began to show signs of approaching collapse.
The storm showed no signs of abating the next day. The bombardons had broken loose from their moorings and had been driven ashore by the force of the wind. They piled up against the whale bridges and subjected those structures to forces beyond their capacity to withstand. Gun crews from all the phoenixes had to be evacuated. High seas were still breaking over to the outer breakwater units, and they had begun to break up. In a desperate effort to relieve the situation, oil was spread on the water outside the breakwater, but with only temporary benefit.
The fury of the storm continued throughout the third day. Disintegration of the outer breakwater became progressively more extensive, and, consequently, the seas within the harbor became even higher.
On the morning of the fourth day, June 22, the fury of the storm began to abate.Wind velocity fell, and the seas decreased in height. Conditions
Seabee Repair Ship at Omaha Beach
Quonset hut houses intricate machinery required for repair operations
remained entirely too severe to permit the resumption
of port operations, however, until June 23.
When the storm was over, Omaha presented a tragic scene. The entire beach was strewn with a confused tangle of wrecked small craft of all types. Most of the floating bridges and pier-heads had been carried away and damaged beyond repair, as had also the bombardons. The mulberry's outer breakwater had lost 19 of the 27 phoenixes which had been in place when the storm broke, although most of those placed in the western breakwater arm were still intact. All the rhinos had had their mooring lines cut by drifting craft and were broached on the beach. Pounding for three days by heavy wreckage had virtually demolished the engines of all 20 of the great barges, and a great many of the rhinos' pontoons had been smashed.
At Utah there were no phoenixes, whales, or bombardons to be damaged. The blockship-breakwater, which had been installed under such hazardous conditions, had fared as well as its counterpart at Omaha; it was battered but still serviceable. The two causeways had had the sand cut away from beneath them by the force of the sea and had settled two to three feet into the beach. Wrecked small craft littered the beach, creating a scene similar to that at Omaha. Rhino operations had, of course, come to a complete stop while the gale was raging.
The mulberry installation at the British beach at Arromanches also suffered from the storm, but the damage was not so extensive as at Omaha. For one thing, the British beach was more favorably situated, farther inside the Bay of the Seine, and within the lee of the Le Havre peninsula, and considerable protection was afforded by the Calvados Rocks, a rocky shoal area just northeast of the harbor installation. For another, the phoenixes at Arromanches were set in water slightly shallower. Moreover, at Omaha the construction work was
about 85 per cent complete when the storm hit, while at Arromanches the work had made far less progress.
When the severe weather at length subsided, there was work to be done on both American beaches. The wreckage had to be cleared away, in order not only to salvage the maximum amount of usable equipment but also to put the beaches again into an operating condition. The Seabees salvaged a number of LCT's, barges, coasters, and small craft.
At Omaha a survey of the mulberry led to the conclusion that it was too far gone to be repaired. As that meant that the gooseberry would be the beach's only protection against the open sea, the blockship installation had to be strengthened. Accordingly, 10 more ships and 21 more phoenixes were brought across the Channel from England and sunk so as to reinforce the gooseberry, by forming a second breakwater immediately inshore from the installation that had been originally laid down.
At Utah the two causeways, which had settled badly, had to be taken up and re-laid somewhat farther west. In the rebuilding, their width was increased to four pontoon strings (28 feet), equal to the causeway width at Omaha; the "blisters" were eliminated; and the length was reduced to 1400 feet.
On June 22, the first day after the storm, the rhinos were back in service at Utah, lightering vehicles and cargo from ship to shore. Because of the great damage done to the barge equipment at Omaha, particularly to the outboard engines, rhino operations there were not fully resumed until July 1.
Marrying rhinos to LST's was discontinued on D-plus-7, for it had been found that the landing ships could be successfully beached. During the first ten days of the invasion, rhinos had accounted for the landing of 5,286 vehicles at Utah and 16,000 at Omaha. Thereafter, they were used to lighter vehicles and cargo from Liberty ships and coasters, the transfer being made by the ships' cargo booms. The causeways continued to carry out the function for which they were intended, the unloading of vehicles from LCT's and personnel from LCI's.
On D-plus-6, work was begun on the beach camp, designed to accommodate 6000 men, that had been planned. Air raids were a nightly occurrence, and foxholes and slit trenches became important items in the facilities provided. By the next day, it was possible for personnel in the bivouac area to begin occupying the pup tents erected in orderly rows along the lines of trenches. Unfortunately, the great number of land mines, still in place, limited the dispersal of the camp facilities; in fact, a number of anti-personnel mines and a few anti-tank mines were encountered even in those areas understood to be "cleared."
Tent erection proceeded steadily during the days that followed, as rhino-ferry crews moved up from the beach and as the number of stragglers and beach survivors mounted. By D-plus-13, all the rhino crews had been billeted ashore.
The population of the camp fluctuated widely; its maximum was reached in the latter part of June, after the great storm, with a total of 3150, which included British as well as American personnel. On one occasion, 12 men from the Norwegian navy were given shelter.
It was found, however, that the camp location left much to be desired; it was too exposed to enemy bombing and strafing. Accordingly, after the great storm had subsided, a start was made on a new camp for Seabee personnel at a more desirable location, and a separate site was selected for a camp for the naval staff. Both new camps were built of pyramidal tents instead of the shelter-halves used for the earlier facility. The 111th Battalion moved into its new quarters late in July;
the other camp was occupied near the end of August.
At Utah, the 81st Battalion erected a tent camp to house 1500 men and 70 officers a short distance behind the beach. This camp included six galleys and a hospital comprising nine tents and one quonset hut. In addition, headquarters facilities for the naval officer in charge were set up, which included two quonset huts, an underground BOQ, and telephone, radio, and visual communication systems for the entire beach.
At the end of the assault phase, however, most of the Seabees returned to England, leaving the 69th, 28th, and 114th Battalions of the 25th Regiment to close up Omaha beach and open the ports at Cherbourg and Le Havre.
The 69th Battalion remained at Omaha, relieving the 111th, worked the harbor as long as was necessary and then closed it by dismantling all its installations. The other two battalions moved to Cherbourg and went to work rebuilding communications systems, re-conditioning war-damaged houses for occupation by naval personnel, and running a transportation pool.
In August 1944, the 114th Battalion arrived in Cherbourg and made ready to carry out its assigned function of rehabilitating French ports still to be captured from the enemy. In London, the Bureau of Yards and Docks set up a small office to make detailed plans for this rehabilitation. Many of the ports for which rehabilitation work was planned, however, were successfully held by the Germans for a long time, and by the time they were taken had been practically demolished by bombing and gun fire. Moreover, the progress of our troops, moving eastward toward Germany, had been so rapid that the western French ports were no longer of vital importance for logistic-support purposes.
When Le Havre fell on September 20, 1944, the 28th Battalion moved to Le Havre to re-construct the harbor which had been badly damaged by Allied bombings and German demolitions. In November, the 114th Battalion moved to Le Havre to relieve the 28th.
Like most of the other Channel ports, Le Havre depended upon locked basins for docking facilities because the average rise and fall of the tide is from 25 to 40 feet. The retreating Germans had blown up virtually all the basin gates, in an endeavor to make the harbor of no use to the conquering Allies.
Army engineers set to work repairing the gates to the locked basins, and Seabees began installing floating piers inside the gates. This was accomplished by bringing rhino barges from Omaha Beach, joining two rhinos to make a pier which was made stationary by driving pilings and was connected to shore by a bailey bridge.
Outside the main sea-wall at Le Havre, the Seabees constructed a 60-by-1,000-foot floating pier of pontoons, which was capable of handling six cargo vessels. On the inshore section of the floating pier, they constructed two timber ramps, each connected with the shore by means of a bailey bridge, built by the Army engineers. With their upper ends resting on pontoon units 5 feet high above the deck of the pier, the ramps were made of such length as to give a ten-percent grade. This same grade continued over the bailey bridges at low tide when their outer ends were down, decreasing as the tide rose until, at high tide, the bridges were horizontal. The piers were moored by pile dolphins placed by Army engineers.
The Seabees also built a pierced-plank airfield at Le Havre. The first strip, built by the 28th Battalion, consisted solely of pierced plank laid on the ground. In building the second strip, the 114th Battalion placed the pierced plank on top of a 4-inch fill which was made of debris from battle-damaged Le Havre and of stones obtained in a nearby quarry. The pierced plank used in this construction had to be hauled 150 miles from Omaha beach.
In addition to the work at Cherbourg and Le Havre, the 28th and 114th also sent detachments to other parts of France. In October, the 28th sent a detachment to Calais on temporary duty. In November, the mobile telephone crew of the 28th was assigned to Paris. The 114th Battalion sent one company to Nantes in August and another company to Pontivy in September.
On November 20, 1944, the 25th Regiment was decommissioned, and the 114th Battalion was formed into CBMU's 627, 628, and 629. CBMU 627, consisting of 25 men and five officers, took
First Seabee Camp On the Normandy Beach
over maintenance duties in Cherbourg, where they remained until June 1945, when they were returned to Davisville. CBMU 628, with a personnel of 350 men and ten officers, handled public works, communications, and transportation in Le Havre until December 1945 when they also returned to the United States. CBMU 629 moved to Paris to repair Orly airfield. In May 1945, a small detachment was sent to Bad Schwalbach in Germany; they returned to Orly in June. In July 1945, work was discontinued at Orly, and the unit was divided, half of the personnel returning to the United States; the remainder moving across the Channel to the United Kingdom.
CBMU 629 was split into four detachments of one officer and six men each. Three detachments worked with small boat units in their preparation for the Rhine crossing, and one detachment worked with an Army Engineer unit.
The first detachment became the first Seabee unit to enter Germany, on December 26, 1944. Later, they assembled pontoon barges on the Rhine at Remagen. These barges were to have been used in connection with strengthening the Ludendorf Bridge. When that structure collapsed, work on the barges stopped.
The second detachment supervised the construction by the Army Engineers of a pontoon pile-
driver barge for use in the construction of a bridge across the Moselle. The rig was completed January 28, 1945. It was later disassembled and transported overland to the Rhine, where it was assembled in preparation for the Rhine crossing. The second detachment also helped load boats for transport to the banks of the Rhine.
The third detachment assembled sea mules along the Meuse River, then built a pontoon pile-driver rig near Maastricht. In March the detachment built sea-mule barges for use as tugs and work barges for bridge construction in the Rhine crossing at Wesel. Operations on the Rhine were carried on day and night; at night, under flood lights; at times, under enemy fire.
The primary function of the fourth detachment was to instruct Army personnel in the assembly and operation of barges on the Meuse River.
After setting up camp in the German barracks at Lettow-Vorbeck Kazarene, a few miles outside the city of Bremen, the Seabees immediately set to work re-roofing buildings where artillery had made huge gaps, installing plumbing and lighting, setting up shops and offices where necessary, repairing harbor facilities, and installing and repairing power lines.
Later, detachments were sent to Bremerhaven and Frankfurt-am-Main. Bremerhaven was to be set up as the main port of entry into Germany for the occupation army. Quarters for officers and men were made livable; dock installations, power lines, and other facilities were repaired. Frankfurt-am-Main was designated as headquarters for the United States Navy for the occupation of Germany.
In the meantime, employment of German civilian labor was begun in Bremen. These men were trained in the shops, transportation, and the operations of the base so that eventually only a skeleton crew of Seabees remained in Germany in supervisory capacities.
Beginning June 22, 1945, the 69th Battalion was flown in echelons from Germany to England.
Source: Building the Navy's Bases in World War II: History of the Bureau of Yards and Docks and the Civil Engineer Corps, 1940-1946, Vol. 2, Chapter 21, pp. 95-120.
Recollections of Vice Admiral Alan Kirk concerning the Rhine River crossing and the capture of Atlantic ports occupied by Germany
Recollections of Lieutenant Commander William Leide during the crossing of the Rhine River in 1945
Recollections of Lieutenant Wilton Wenker and Lieutenant Elby concerning the crossing of the Rhine River in 1945