BOMBARDMENT AND OTHER DEFENSIVE OPERATIONS AGAINST ENEMY LAND FORCES
GENERAL BOMBARDMENT PLANS
A. Coordination of Naval and Air Bombardment
- The various measures taken to protect NEPTUNE from German Naval and Air counter action have been described in the preceding chapter. Comparable measures were taken to protect NEPTUNE from the hazards of the German shore defenses. The principal means employed was bombardment.1 Other measures employed included Diversions, Radar Counter Measures and the use of smoke.
- The primary object of the bombardment program was to prevent German coastal batteries, in the vicinity of the assault area, from interfering with the safety of allied ships and forces. The Germans had installed some 25 major batteries, composed of heavy and medium guns, in various casemated emplacements covering the sea approaches and anchorages to the assault area. If these batteries had been allowed an uninterrupted opportunity they would have been able to defeat the NEPTUNE assault before it reached the beaches. The locations of these batteries and their area of fire, in relation to the positions of allied assault forces, are shown in the accompanying sketch.2 In addition to fixed coastal artillery, the Germans had an indeterminate quantity of mobile heavy artillery, which might be rapidly brought into the Seine Bay area to reinforce these fixed batteries.
- A secondary object of the bombardment program was to support the assault and subsequent operations ashore, by neutralizing or destroying beach defenses, enemy concentrations and other targets impeding the army's advance. In this role, bombardment was employed to flatten beach obstacles, to explode beach mines, to neutralize infantry positions and batteries shelling the beach, and to engage counter attacking formations.
The bombardment policies followed were those developed
in the Graham Report on "Fire Support of Sea-Borne landings
against a Heavily Defended Coast". This report laid down
two basic principles:
- Casemated batteries probably could not be destroyed by bombardment, but could be sufficiently neutralized to render them acceptably ineffective until the army could capture them. The report also calculated in detail the weight of fire required to do this.
- Beach defenses could best be neutralized by "beach drenching," which would force the defender underground and numbs his mind and nerves. Aimed fire in the dust and smoke of battle would be less likely to accomplish this. Bombardment was recognized to be a combined naval, air, and army task, but until the army was well established ashore the job had to be done principally by air and naval forces. The NEPTUNE bombardment plan was prepared by the joint action of the three Service Commanders, under the general supervision of SCAEF.1
The broad outlines of the Joint Fire Plan were:-
- Coordination of the Bombardment effort, final selection of targets, and the assignment of priorities was assured by the three C's-in-C;
- The targets for air and naval bombardment were so selected that priority could be given to those targets which would interfere most with the approach of the Naval Forces;
NEPTUNE targets were to be bombed from the air
prior to D-day, at least once and oftener if possible,
but the air effort allotted to the task was limited
- The necessity of bombing batteries in other areas to prevent the Germans from ascertaining the intended point of invasion; and
- By air operations, immediately prior to D-day, designed to distract attention from the assault area.
- During the night preceding H-hour, the heavy night bomber effort was to be concentrated on ten selected batteries in the assault area, this number being the limit of availability of night bombing aids.1
- During the first light of D-day (that is during the 30 to 60 minutes before H-hour a proportion of the medium (day) bombers were to concentrate on 6 particularly dangerous German batteries.
- During the last 40 minutes before H-hour, Naval Bombarding forces were to engage all of the German batteries in the area with maximum fire.
- During the balance of the assault, these batteries were to be engaged with further counter battery naval fire to the extent required to keep them silenced.
- Fighter bombers were also to be employed in post H-hour counter battery bombardment.
- Commencing at about 40 minutes before H-hour (that is during the final approach of the landing forces) the entire available heavy and medium day bomber effort was to be concentrated on the neutralization and destruction of beach defenses (beach drenching).2
B. Air Bombardment Program
- The Allied air forces, operating in accordance with this general plan, for putting dangerous batteries out of action before allied ships came within their ranges,executed a long series of bomber attacks for many months preceding the invasion.1 The primary object of these operations, the obstruction of the enemy's program of building concrete emplacements for his coastal field batteries, was only partially achieved. On D-day, there were more concreted emplacements than could be dealt with by available battle ships and monitors.2 This program of air bombardment of the Seine Bay batteries was a part of the larger air forces offensive, POINTBLANK. An exclusive concentration on Seine Bay targets would have indicated to the Germans the intended assault area. In order therefore to preserve that secret, pre D-Day aerial bombardment of coastal battery targets was uniformly dispersed over the entire northern coasts of France and the Low Countries. The air forces had, however, succeeded, before D day, in bombing the most dangerous batteries in the Bay of the Seine at least once.3
During the night preceding D-day, 1,136 heavy bombers of R.A.F. Bomber Command dropped 5,853 tons of bombs on the 10 most dangerous batteries in the NEPTUNE area.4
As daylight came 1,365 heavy bombers of the 8th U.S.
Army Air Force took over. In the 30 minutes preceding
H-hour, they were scheduled to drop 4,200 tons of bombs
in a "beach drenching effort" on the beach defenses of
all beaches, although, when the time came, no bombs at
all were dropped on Omaha beach. Their total effort
was 1,365 bombers, with 2,796 tons of bombs. The
failure of the U.S. Army Air Force to carry out its
assigned task at Omaha beach made the assault there
much more difficult and costly than at the other beaches.1
- Medium and light bombers, just before H-hour, delivered their bombs on the six selected targets. These, and fighter bombers, continued throughout the day to attack special inland and coastal defense targets with light bombs, rockets and gunfire. Later in the day the U.S. 8th Air Force came over with 2,627 heavy bombers and 1,347 escorts with which it dropped 1,746 tons of bombs at targets requested by the army.2
GENERAL BOMBARDMENT PLANS
A. Naval Bombarding Forces
Naval Bombardment was designed to accomplish the
- Neutralization of German coastal defense and inland batteries capable of bringing fire to bear on NEPTUNE sea approaches, anchorages or beaches until each battery was captured or destroyed;
- Neutralization or destruction of beach defenses during the final approach and assault, and
- Support of the army after the assault by engaging mobile batteries, counter attacking formations, defended areas, etc., particularly during that period when the army artillery was not fully deployed.1
- Naval bombardment was carried out by the following heavy forces: 7 Battle Ships,2 2 Monitors, 23 Cruisers, 2 Gun Boats and 74 Destroyers.3 In addition, a wide variety of special amphibious fire support craft were provided, to give close support by firing onto the beaches from inshore waters. This force consisted of 25 LCG (L's) 36 LCT (R's), 24 LCS (M's), 29 LCF's, 45 LCA (HR's), 5 LCT (CB's), 48 LCT (A's), and 16 LCT (HE's).4
- ANCXF allocated firing ships and craft between the
Western and Eastern Task Forces partly on the basis of
nationality and partly on the basis of requirements.1
The Task Force Commanders allocated Bombarding Forces
within each Task Force to meet special requirements.
The entire force of close support craft were allotted
to assault forces and all were employed in the barrage
of drenching fire laid down just before the landing
began. About nine tenths of the heavy ships were also
allotted to the assault forces. The remainder were
held in reserve to relieve ships which sustained severe
battle damage or had depleted their ammunition. The
allocation of firing ships to these various purposes is
shown in Chapter IV section 5-E-(2). In general, the
two wings were allotted a heavier proportion of naval
bombarding forces, to keep the batteries on the flanks
of the land front neutralized.
- Command of Bombarding Forces in the Eastern Task Force was exercised by a Commander, (Bombardment). Direct Control of Bombardment Forces was retained by the Assault Force Commander and was not delegated to the Assault Group Commanders. In the Western Task Force, the bombarding forces were assigned to independent task groups in each assault force, and the management of the firing ships was left to the task group commander.1 Command of fire support craft, in each assault force, was exercised by a separate task group Commander.
- The heavier bombarding ships were assembled for the most part in the Clyde (British Forces) and at Belfast (U.S. Forces).2 They were sailed in 5 convoys so as to rendezvous in the assault area with the appropriate assault forces. They made the cross channel passage and approach in the fast convoys lanes of each assault force.3
- Bombarding destroyers were used as escorts during the passage and approach and were assigned to escort convoys whose destination and scheduled time of arrival corresponded with their bombardment tasks. Fire support craft were sailed in convoy with the assault groups with which they were scheduled to operate. In order to protect bombarding ships from the danger of enemy mines inside German Mine Barriers, special minesweepers were ordered to sweep the flanks and clear the bombarding positions.4
B. Pre-Arranged Bombardment Schedule
- There were 25 heavy and medium batteries situated in the Bay of the Seine, capable of bringing fire to bear on Allied ships in the assault area and on troops and boats near or along the beach.1 In addition, there were 2 batteries within range of naval firing ships capable of harassing airborne troops landing near Isigny.2 By the pre-arranged plan, these batteries were apportioned out among the bombarding ships who were to begin fire at the pre-arranged time.3
- In order to ensure accuracy in the naval bombardment of pre-arranged targets, Spotting Aircraft were detailed to arrive before sunrise and to observe the fire from all heavy ships. In the Eastern Task Force, bombardment was begun 40 minutes before sunrise and continued until H-hour. This allowed 130 minutes of fire. In the Western Task Force, fire was opened at H minus 40 minutes and directed against beach targets until H-hour and then against inland targets for another 20 minutes.4 Fire was continued after H-hour against batteries and strong points on the flanks for varying periods, based on the time it was expected troops would reach the various phase lines.
- In order to assist in blasting a path through the beach obstacles and to neutralize local beach defense strong points, all fire support craft and all heavy ships, not engaging enemy batteries, opened up at H minus 40 minutes with all the fire power at their disposal, to drench the beach until H-hour with the maximum weight of naval bombardment.1 The object of Beach Drenching was to put down as heavy a barrage as possible with the object of numbing and demoralizing the defenders. Except in special cases, aimed fire, with the object of destroying specific enemy positions, was impracticable at that stage because the smoke and dust of war made accurate observation impossible.
C. Post H-Hour Aimed Bombardment
On completion of the initial barrage bombardment,
naval bombarding forces stood by in the assault area to
deliver aimed fire on special targets. These targets
- Re-bombardment of coastal batteries when and if they returned to action
- Special strong points or obstacles impeding the advance of the army and enemy emplacements, and
- Strong points inland for which the army required artillery support.
- As this fire had to be delivered in close support of the army and would fall very close to positions occupied by allied forces, careful arrangements were required to observe targets and the fall of shot. Three types of spotters were used; (1) Shore Fire Control Parties (SFCP);2 (2) Air Spotters; (3) Air Observation Posts (Air OP).
- Shore Fire Control Parties were allotted on the basis of one party per assault battalion. In the U.S. Sector 27 Shore Fire Control Parties were organized, of which nine were assigned to each assault infantry division. In addition, nine naval gun fire spotting teams, consisting of one Army Paratroop Officer and two enlisted men, were dropped by parachute with the 101st Airborne Division. The personnel of each shore fire control party was one Army Officer, one Naval Officer, and twelve enlisted men. Each party was supplied with a Jeep, an M.14 Half-track, and had both a frequency modulated and an amplitude modulated radio transmitter-receiver. In the British Sector, 39 F.O.B. Parties were provided, one accompanying each British Army battalion. In both Sectors, a Naval gun fire liaison officer was attached to each regimental fire control center in order to direct the activities of the three shore fire control parties in his section. In addition, a Naval gunfire officer was attached to each divisional headquarters in charge of all shore fire parties in his division.
Every firing ship was provided with an army artillery
officer, charged with maintaining up-to-date information
about the position of allied troops and with determining
the desirability of firing at any given target. The
organization worked as follows:
- The Shore Fire Control Party made contact with his firing ship by radio link and designated a target by reference to a grid;
- The Army liaison officer decided whether it was safe to fire at that target;
- The ship itself controlled the fire.
- The Shore Fire Control Party observed the fall of shot and corrected fire by a means of a clock code.
- Shore Fire Control Parties were sent on to the beaches as early as H plus 30 minutes. As a result of landing so early, their equipment suffered considerable damage. It was not until Regimental Headquarters were established ashore and the early confusion and fluid conditions on the beaches had been stabilized, that their parties were able to do their job effectively. Even then they were subject to interruption. The Germans possessed and used extremely
effective D/F equipment. They were able to locate key
radios, particularly in the medium frequency band, and
take then under fire in a matter of seconds.1
- The second form of bombardment spotting was by aircraft. Spotting was carried out by 104 single seater aircraft operated by the R.A.F., Royal Navy, Fleet Air Arm, and U.S. Naval pilots in British planes. Single seaters were used because it was believed by the A.E.A.F. that high casualties would result if aircraft of low speed were employed. The ordinary two seater observation plane was so slow that it was easily put out of action by enemy anti-aircraft guns or fighters.2 Spotting by single seater aircraft had never before been undertaken on a large scale, but none the less, it was very successful. These spotting aircraft operated in pairs, one plane acting as a spotter and one as escort. Planes were capable of doing either job interchangeably. Both planes operated on the same radio frequency and in contact with the same ships. Spotting aircraft were formed into a pool which was situated at Lee-on-Solent. No attempt was made to attach individual pilots to individual ships, because of the limited availability of both pilots and ships for training, and because of the much larger number of aircraft which would have been required.
- The organization employed was changed during the course of the Operation. It was originally intended that spotting aircraft would be retained on call at Lee-on-Solent and that the pilots should be briefed before taking off on two targets. The initial targets were those laid down in the fire plan, and at a later date those specially requested by the Army. In practice, it was found, after the pre-arranged targets had been dealt with, that most shots were impromptu. Pilots were briefed in the air on the way to the assault area. Even when pilots were briefed on specific targets before they left the ground, it was found that they were required afterwards to observe on different targets. The policy was therefore adopted of reducing delay by maintaining a few aircraft continuously in the air over the assault area, instead of keeping them on call at Lee-on-Solent.
This required that every ship should be capable of working
with any aircraft, and radio crystals for all bombarding
frequencies were provided to each vessel. When a ship
required air spot, it made radio contact with a plane in
the area. The plane then located the target and gave the
exact location to the ship by means of a grid reference,
on a pre-arranged gridded map, from which the ship directed
its own fire. The plane then observed the fall of shot and
gave corrections as required on the basis of the clock code.
Owing to the shortage of aircraft, one plane was often
employed to spot for two or more ships.
- The third method of observing fire was by the employment of Army Air Observation posts. These were small light aircraft, usually Piper Cubs or Austers, which spotted for the shore fire control party, which in turn relayed the information back to the ships. In all cases, it was the responsibility of the ship to determine whether any given shoot would endanger allied personnel or positions. To enable the ship to do this, each ship was provided with an Army officer who was kept up to date on the positions of allied forces ashore.
D. Ammunition Supplies
- A comprehensive program for replenishing stores of ammunition in all firing ships had been carefully worked out prior to the operation. These arrangements provided for holding certain ships in reserve, so as to take over bombarding duties when the initial ships had expended their outfit, and also for the employment of destroyers and other ships in dual roles of bombardment, escort and screen.
- The Admiralty provided stowage afloat in lighters and ammunition ships for the majority of large calibre ammunition to permit rapid reammunitioning. One refill of main battery ammunition for U.S. Battleships and Destroyers and two refills for U.S. Cruisers was available. 14", 12", 8" and 5" ammunition was held in Plymouth, and 8" and 5" ammunition in Portland and Southhampton. U.S.S. Nitro carried the majority of ammunition for U.S. ships in Plymouth. Quick ammunitioning was accomplished in all cases. In one particular case, the U.S.S. Nevada main battery was replenished in 20 hours.
- For British ships, there was average of two outfits, per bombarding ship, held in reserve afloat in the Isle of Wight area and in other southern English ports. Small calibre ammunition was available for all Landing Craft and other smaller vessels at all south coast English ports. Five British Ammunition Store Issuing Ships (ASIS) were stationed in the assault area to replenish small ammunition for Landing Craft, Gun Support Craft and light vessels which remained on the far shore. Ammunition carriers were also provided for the purpose of replenishing the stores of the issuing ships. The entire program of reammunitioning worked admirably and the bombarding forces never were in a position in which they did not have sufficient ammunition in hand to meet all demands.
E. Results of Naval Bombardment
- A generalized tabulation of the results of Naval bombardment is hard to give.1 Prisoners reports indicated that the terror of the gun fire from ships at sea was a major factor in driving the Germans from their positions. Subsequent to the assault, considerable trouble was experienced on both flanks from enemy guns which shelled the beaches and anchorages. Although doubtless new guns were rushed up by the enemy to replace those made unserviceable, there is no evidence that naval gun fire caused great destruction to enemy guns.
- Naval gunfire neutralized rather than destroyed enemy batteries. The long periods of silence of flanking batteries, which often followed bombardment, was considered to be the result of the moral effect of H.E. on the defenders rather than of its destructive effect. In the rapid advance along the Cotentin Peninsula, hostile batteries which could fire on the Western beaches were captured at an early date. On the Eastern static flank, an enemy battery east of the River Orne and another at Le Havre made it necessary to discontinue unloading on Sword Beach. All Navy and Army reports covering the subject are agreed that the close supporting fire delivered by small ships, immediately preceding H-hour, was of the greatest assistance in enabling the Infantry to make the first break across the open beaches.
German reports on the effect of Naval bombardment
are equally eloquent concerning the damage which it did
to the German defenders. The following extract from
the German Military Journal was broadcast over the German
"Militarische Correspondenz aus Deutschland" depicts the part played by the guns of the Navy at the invasion coast.
"The fire curtain provided by the guns of the Navy proved to be one of the best trump cards of the Anglo-U.S. invasion Armies. It may be that the part played by the Fleet was more decisive than that of the air forces because its fire was better aimed and unlike the bomber formations it had not to confine itself to short "Bursts of Fire".
"Fire power of warships must not be under-estimated:- While the first troop landings were in progress and no bridgehead existed the invasion forces had only little artillery at their disposal. It was, however provided to very high degree by the combined Anglo-U.S. Fleet. It would be utterly wrong to under-estimate the fire-power of warships even of smaller vessels. A Torpedo Boat for instance had the fire power of approximately a Howitzer Battery, a destroyer that of a Battery of Artillery.
"Equivalent to an unusually heavy artillery barrage:- With regard to its armament a cruiser may be compared with a regiment of artillery. Battleships carrying 38 cm. or 40 cm. guns have a fire-power which to achieve in land warfare is difficult and only possible by an unusual concentration of very heavy batteries.
"Great mobility of these "Floating Batteries":- Of particular advantage to the invasion troops which employed strong formations of warships as floating batteries was the great mobility of the vessels by which artillery concentrations could be achieved at any point of the coast and to change the place according to the exigencies of the fighting situation. The attackers have made the best possible use of this opportunity."
"An umbrella of fire:- Repeated strong formation of warships and cruisers were used against single coastal batteries thus bringing a quite extraordinary superior fire-power to bear on them. Moreover time and again he put an umbrella of fire (Feuerglocks) over the defenders at the focal points of the fighting compared with which incessant heavy air attacks have only a modest effect."1
The following extracts which are from a report on
the Invasion of France by Field-Marshall von Rundstedt,
likewise shows the great advantage which the Allies
derived from Naval Fire Support.
"Facts must be emphasized
- "The enemy's complete mastery of the air.
- "The skilful and large scale employment of enemy parachute and airborne troops.
- "The flexible and well directed support of the land troops by ships' artillery of strong English naval units ranging from battleship to gun boat ......"
...... The enemy had deployed very strong naval forces off the shores of the bridgehead. These can be used as quickly mobile, constantly available artillery, at points where they are necessary as defence against our attacks or as support for enemy attacks. During the day their fire is skillfully directed by . . . . . . plane observers, and by advanced ground fire spotters. Because of the high rapid-fire capacity of naval guns they play an important part in the battle within their range. The movement of tanks by day, in open country, within the range of these naval guns is hardly possible".1
GENERAL BOMBARDMENT PLANS
A. Bombardment of Cherbourg1
- The initial plan provided bombardment at 28,000 yards, to neutralize or destroy long range batteries, after which, ships were to close in to a position roughly 14,000 yards north of Cherbourg. The long range bombardment was, however, cancelled shortly before the commencement of the operation. This was considered necessary by the U.S. Army Commanders to avoid any danger that U.S. troops, who were already close to Cherbourg defences, might advance into the firing zone. Bombarding ships, therefore, proceeded into close range position before opening fire. A congested situation developed at the southern end of the approach channel, where the Nevada, Quincy, Tuscaloosa, Glasgow and Enterprise were forced to reduce speed to keep clear of the minesweepers when the whole force was turning eight points, from the approach channel, into the fire support area.2
- Support of the advance of the VIIth U.S. Army Corps up the Cotentin Peninsula, and of its capture of Cherbourg, was organized at the request of the Commanding General, 1st U.S. Army by CTF 122. A Bombarding Force (Task Force 129), was organized which on June 25, 1944, bombarded enemy batteries and shore defenses guarding the approaches to Cherbourg. Task Force 129 was under the Command of Rear-Admiral Deyo, USN, (CTF 129) flying his flag in the U.S.S. Tuscaloosa. Second in command was Rear-Admiral Bryant, USN, flying his flag in U.S.S. Texas. In addition to these two ships, the force comprised: U.S. Ships, Arkansas, Quincy, Nevada, Laffey, Barton, O'Brien, and H.M. Ships: Glasgow and Enterprise. The British 9th and 159th minesweeping flotillas and U.S. 7th M/S Squadron, provided minesweeping protection, and an anti-submarine screen to the force was provided by H.M. Ships, Onslow, Offa, Onslaught, Oribi, Melbreak and Brissenden.
- While the ships were in this awkward position, turning at slow speed, the enemy opened fire at 1206 with initial accuracy. Destroyers made smoke, bombarding ships increased speed and, in some cases, had to proceed into unswept waters to obtain manoeuvering room. By 1212 all ships had opened fire by air spot on Army designated targets, but fire was soon shifted in many cases, to batteries which were straddling ships. The batteries, whose accurate fire gave most trouble, were chiefly those which, under the original plan, would have been destroyed at long range.
- The Nevada was straddled on 23 occasions, and several near misses covered her decks with water and splinters, but she was not hit. However, frequent use of helm and drastic alterations in speed while shell dodging was thought to have diminished the accuracy of her own fire. When she ceased fire at 1525 she had expended 112 round of 14" and 167 round of 5". The Texas received a direct hit on top of her conning tower which wrecked the navigational bridge and facilities. Glasgow, O'Brien, Laffey and Barton also sustained hits and damage varying in degrees. Casualties to personnel in all ships were reported as 13 killed, 86 wounded. Bombarding forces withdrew at 1530 when it was reported that all but possibly two batteries been silenced.
RADAR COUNTER MEASURES
A. Radar Countermeasures1
The enemy was known to have an effective and well
integrated chain of radar sweeping and gun control stations
along the invasion coast.2
With these he could provide himself with:
- Early warning of the approach of allied invasion forces;
- Radar plots of the movement of allied vessels; and
- Accurate ranges and bearings for the control of his coastal guns.
One of the tasks which the navy, in conjunction with the air force, was required to accomplish was that of neutralizing enemy radar. This presented a problem of considerable magnitude, especially as it was essential that some 80 minesweepers should approach within detection range of enemy radar ten hours before the assault. The first step was to acquire detailed intelligence concerning:
- The location and interconnection of enemy radar stations and networks, and
- Technical details of the types, frequencies, characteristics and capabilities of his various instruments.
- A COSSAC committee, made up of representatives of all the services, began the accumulation of the necessary information at an early date. After SCAEF assumed the direction of the operation, this committee was carried on as a department of his staff. In the end detailed and accurate intelligence became available, derived from air reconnaissance, from radar monitors and from other sources. ANCXF was given responsibility for operational policy and general orders, governing the use of R.C.M.3 In November 1943 a joint Navy-Air R.C.M. Plan was evolved. This plan provided for the following measures to be taken to counter enemy radar.
- Bombardment (Air and Naval) of enemy radar stations and networks was the first and principle means of neutralizing enemy radar. The effect of bombardment was to destroy many stations and unnerve the operators at others, thus making them less critical of the jamming and deception being used. Over 1,400 air sorties were flown against suitably random sites. In the area effecting the main assault, which for Radar purposes was between Cap d'Antifer and Cap Levi, the principle twelve sites containing 44 sets were rendered inoperative, at least temporarily. Allowing for repair of minor damage and subsequent attacks, it was estimated that about 20 out of the original 44 sets were operative on the night of 5/6th June. The heavy air and naval bombardment preceeding the assault further reduced this figure. Only eight enemy radar stations were definitely heard transmitting during the night of the assault.
- The second method of neutralizing enemy radar was by interposing an R.C.M. screen between enemy radar sites and approaching assault forces. This was done in part by routing diversionary forces so as to pass in a westerly direction along a route to the shoreward of the convoy route. Full particulars of this operation are given in the next section of this chapter.
- Further support by the Air Force was obtained by "Window" laid on the East Flank of the main assault to add to the confusion of the enemy. Special window filled rockets and shells were carried by bombing ships to supplement their electronic R.C.M. in case of need. They were also accompanied by M.M.S. towing reflector balloons in order to multiply echoes and confuse the enemy's point of aim.
- In order to interpose an anti radar screen, between enemy shore radar stations and the assault area, the following measures were planned and executed:-
- An inshore screen was provided by installing some 240 low power sweeping and locking jammings in LCT(A)s and LCG(L)s. These vessels were selected to carry the inshore jammers because their primary mission, which was to sail up to the beach, concurrently with the assault landings, in order to deliver close fire support, would site them in a favorable position to interpose an R.C.M. screen.
- An offshore screen was established by installing some 60 medium power sweeping and locking jammers in certain minesweepers and destroyers. Vessels were chosen for this job from those whose primary mission would keep them in or near the assault area during the critical period.
- Certain individual ships, in general bombarding ships, carried R.C.M. as a part of their standard equipment, and an additional 120 high powered hand tuned jammers were fitted in these ships. This equipment was intended primarily for the protection of the individual ships, but every ship was also expected to augment the offshore R.C.M. screen when required.
- Balloons fitted with radar reflectors, capable of making an impression on enemy radar similar to that made by a ship of a certain size, were towed into the assault and bombardment areas to confuse the range and point of aim of coastal batteries.
- In order to control the propagation of the R.C.M. jamming screen, 12 monitoring receivers were installed on headquarters ships. These were tuned to the frequencies which the enemy used for radar emission, and, when an enemy radar was detected, the force commander directed R.C.M. screening vessels to close the gap by suitable jamming.
- Careful coordination in the use of R.C.M. was essential, especially in the early stages of the operation, as it was necessary that the enemy should not detect the allied approach, either by the direct use of radar or by monitoring R.C.M. emissions. If R.C.M. were turned on too soon, enemy R.C.M. monitors would be alerted; if it were turned on too late, enemy radar
- Another R.C.M. requirement was to screen convoys, including a build-up force, while passing through the straits of Dover. This involved enlargement of an existing chain of shore stations, and the intensive use of smoke. As a result only six of the 2,127 ships that passed through the Strait were damaged by fire from enemy shore batteries.
- Production of much of the equipment required for this program had never before been undertaken. The question of supply and production had therefore to be solved. It was agreed that the U.S. Navy would supply 250 sets and the Royal Navy 350 sets. Production requirements were substantially met. A total of 603 electronic radar jammers were employed, of which 371 were of American manufacture and 232 British. 351 of the 371 American equipments were of a design originally intended for aircraft. 207 of the 232 British equipments were also types designed for aircraft. 64 guided missile jammers were employed, 28 of American manufacture and 36 of British, 16 of the 28 American equipments were converted aircraft jammers, 36 balloon reflectors and 18 Moonshine equipments, all British were employed.
- Frequencies were allocated on the basis of the radio-radar spectrum allocation promulgated by the SHAEF Signal Board, the intended disposition of forces and the known location and ranges of enemy equipment. Several large scale trials were held to assure that the completed plan would function as intended. Fitting and tuning of sets proved a problem because of the late date at which the equipment was available. About 85% of the intended program was completed before sailing. To provide operators to man the new equipment employed, a special school was constituted at which 86 radar and radio men were given a 5 day course of instruction.
would pick up the movement of assault forces.
There was no precedent to act upon, but a plan was
adopted by which transmissions were to be begun by
loading units at a specified time, and by the
remainder, on crossing a certain latitude. Flexibility
was provided, to allow last minute adjustment
by ANCXF, in case propagation conditions might be
expected to deviate from normal. Transmissions
were actually begun at 2130 on D-minus-1, by minesweepers
which were at that time fifteen miles off
Cap Barfleur. Other ships switched on when south
of latitude 50° 05' N.
One of the defensive tasks undertaken by the Navy
was to execute diversionary operations. These diversions,
which were supported by air operations but which
did not involve the landing of troops, were carried out
more or less concurrently with the actual landings.
Light naval forces, fitted with special equipment,
approached certain beaches outside the assault area
shortly prior to H-hour to simulate the threat of landings.
The simulation was largely effected by the use
of radio deception, radar, radar counter measures, sonic
devices and the use of smoke. The object of these
diversions was primarily to cause the enemy to delay the
movement of his military reserves to meet the real
invading forces. Secondary objects were to provoke a
naval engagement which would draw enemy naval opposition
away from the assault forces. The general plan was to
make several feints at the enemy shore at approximately
the same time as the real assault forces approached the
The feints were made as follows:
- Operation GLIMMER was a feint in the direction of Pas de Calais designed to simulate an amphibious attack by one infantry division and a naval force equivalent to that of one assault force. The operation was carried out by a force of six M.D.M.L's (70 foot motor launches) which were placed under the orders of Vice Admiral Dover, who was responsible for the execution of the operation in accordance with the detailed plan and technical instructions of ANCXF.
- Operation TAXABLE was a feint in the direction of Cap d'Antifer, designed to simulate a landing by one infantry division and one naval assault force. It was carried out by a force of eight H.D.M.L's operating under the direction of Vice Admiral Dover, in accordance with detailed ANCXF instructions. It was sailed with Force S and its radio deception was arranged to as to give the appearance that Force S and the 50th division were actually preparing to land near Cap d'Antifer.
- Operation BIGDRUM was carried out by a force of four H.D.M.L's under the command of the Naval Commander, Force U. It was routed so as to pass in a westerly direction along a route to the shoreward of the approach route of Force U. It would thus screen the movement of Force U from enemy radar located in the vicinity of Barfleur, and would so occupy the attention of enemy radar during the passage of the assault forces as to confuse him as to the progress of the main force.
- Operation ACCUMULATOR was a small diversion executed in the Channel Islands area by two destroyers, H.M.S. Haida and H.M.S. Hurron1 on the 12th and 13th of June, several days after the assault. This diversion was intended to give the Germans the impression that a landing was to be carried out in the vicinity of Granville on the west coast of the Cotentin Peninsula. The object, which appears to have been achieved, was to hold enemy troops in the neck of the Peninsula while the U.S. Army was in the process of cutting across its base.
The effective simulation of real operations in these
diversions, was achieved by the following means:
- "Window"2 were dropped from aircraft. These had been specially designed to create the illusion of enemy radar of ships of various sizes lying to seaward.
- "Moonshine", produced by hand turned transmitter receivers, giving the same effect on enemy radar monitors as if radar search were being conducted, was disposed in imitation of amphibious force approaching an assault area.
- Balloons, mounting radar reflectors, designed to give a response on enemy radar equivalent to that of 5,000 ton ship, were flown from vessels and tows. On departure from the area, those balloons were moored to give the impressions, both visually and by radar, that assaulting forces were lying off the beach.
- Standard obstruction and jamming devices were also used, to lead the enemy to believe that an amphibious force was trying to conceal its presence and strength from radar ashore, and also to prevent enemy radar from learning the true composition of the diversionary force.
- Smoke was laid between the balloons and the shore to further the impression of an enemy force lying to seaward.
- Sonic effects, in imitation of the noises made by naval forces assaulting a beach, were produced, but it is probable that the effect of these was lost in the sound of the surf which was running very high that night.
- Radio deception was staged. Several additional radio transmitters and receivers, installed aboard the diversionary forces, put out a radio program closely approximating the emissions of an assault force just breaking radio silence and carrying out the early tasks of an assault.
- The entire diversion was coordinated with the large scale radio deception operations, carried out on the east coast, so that enemy could not discern the deception by observing the fact that no such forces had been previously reported as being available to carry out such an assault as that simulated.
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p.458 #1 The role played by bombardment was partly defensive and partly offensive. It contributed to the defense of NEPTUNE, in that it was employed in the neutralization of shore batteries whose fire endangered ships approaching or in the assault area. It was offensive, in that it was employed to blast a path for assaulting troops through the enemy beach defenses and coastal fortifications.
p.458 #2 For details of the German coastal batteries see Chapter IV, section 1-e. The fire of these batteries had been "gridded" in advance so that they would be able to shoot with a high degree of accuracy.
p.459 #1 Serial 5 to NJC 1004 of 1 February 1944.
p.460 #1 This was to be a R.A.F. bomber command effort as the U.S. heavys did not employ the appropriate bombing aids.
p.460 #2 4,200 tons were to be dropped by air forces.
p.462 #2 ANCXF report Vol I, Page 64.
p.462 #3 These were: (a) Le Grand Clos (Le Havre) (b) Fontenay Sur Mer (c) Benerville (d) Houlgate (e) Points du Hoe (f) Riva Bella (g) La Pernelle (h) Sallenelles (i) Morsalines (h)Villerville. (See ON-8).
p.462 #4 This night effort was accomplished by "instrument" aiming - R.A.F. did the job because the U.S.A.A.F. was not fitted with the necessary instruments. The batteries bombed were: Points du Hoe, La Fenelle, Fontenay Sur Mer, Morsalines, St. Martin de Vaueville, Sallenelles, Houlgat, Benerville, Barfleur, Riva Bella. (See report of C-inC AEAF).
p.463 #1 See Report of NC Force O as reprinted ANCXF Report Vol III Page 6.
p.463 #2 For air bombardment figures generally see NEPTUNE report of C in C AEAF.
p.464 #1 See ON-8
p.464 #2 Including one in reserve
p.464 #4 An LCG(L), Landing Craft Gun (Large) was a converted LCT(3) or (4) mounting two 4.7" guns on a false deck built over the hold. It was designed to provide close supporting fire during the assault and subsequent advance. It was approximately 187 feet long, had a speed of 7 knots and used diesel fuel.
LCT(R), Landing Craft Tank (Rocket), was a normal LCT(3) fitted with 5" rockets projectors. It was capable of firing 800 to 1,000 rockets, so as to provide high explosive drenching fire on an area target prior to touch down of the first landing craft. She had an overall length of 160', a speed of 8 knots and used diesel fuel.
LCS(L), Landing Craft Support (Large) was an early model LCT converted so as to mount one two pounder gun, two .5 oerlicons, one 4" mortar and 2 small oerlicons. It was used to support the assaulting forces by light artillery fire from close inshore. She was a 104' vessel capable of 11½ knots speed, using gasoline for fuel.
LCS(M), landing Craft Support (Medium), was an LCA converted so as to mount one 4" mortar, two .5" guns and other miscellaneous anti-aircraft guns. It was used to provide close support for landing parties by means of military gun fire and smoke cover. It was capable of being hoisted fully loaded, having a length of 40', a speed of 7 knots and using gasoline.
LCF, Landing Craft Flack, was a converted LCT(3) or (4), equipped with eight 2 lb. guns and 4 - oerlicons or four 2 lb. guns and eight oerlicons. It was used to provide protection for assault forces against close range air or E-boat attack. It was capable of being used in a secondary role as close support. It had a maximum speed of 7 knots and used diesel fuel.
LCA(HR), Landing Craft Assault (Hedge Row) was an LCA capable of projecting 24 H.R.'s (60 lb. bombs) the blast from which was capable of blasting a path through wire and anti-personnel mines. Length approximately 45 feet.
LCT(CB), Landing Craft Tank (Concrete Buster), was an LCT rigged to carry two or three tanks each mounting 17 lb. guns capable of being fired from the vessel, in order to provide a high velocity fire for attacking concrete.
LCT(A), Landing Craft Tank (Armoured), was a converted LCT(5) specially armoured and carrying two or three tanks mounting 95mm guns, two of which were capable of being fired from the ship. It was used to provide close support for the assault, using high explosive shells.
LCT(HE), Landing Craft Tank (High Explosive), was the same thing as an LCT(A) but unarmed.
p.466 #1 As originally planned, the Royal Navy was to supply the entire bombardment commitment. As the scale of the operation gradually expanded, and as the Germans in 1943 and 1944 rapidly transformed their batteries from open gun positions to heavily concreted emplacements, the requirements for Naval Bombardment mounted steadily. As the Royal Navy did not have the resources to meet the entire added requirement, the U.S. Navy was called on to make up the difference. In the end the U.S. Navy provided a good third of the Bombardment commitment. The way in which the bombardment commitment grew may be seen by comparing Admiral Ramsay's estimates of requirements (a) for ROUND-UP (b) initial OVERLORD estimate made in November 1944 and (c) final allocation to OVERLORD,
Estimate (Nov. '43)
|Close Support Craft||48||200 (approx.)||242|
See Operation Round-up 1943 Provisional Assessment of Naval Implication Admiralty 051404/42 of 16/7/42; Appendix H to COSSAC Plan; ANCXF Report Vol. 1b. 25 and b.29.
p.467 #1 In Force O, the bombarding ships were TG 124.9 under command of Admiral Bryant USN, in USS Texas. In Force U, the bombarding ships were TG 125.8 under command of Rear Admiral M.L. Deyo USN in USS Tuscaloosa.
p.467 #2 Augusta, Scylla and Destroyers required for escort were assembled with the assault forces on the South Coast.
p.467 #3 They crossed the channel closely behind the minesweepers so as to be able to afford the minesweepers protective fire in case German Batteries opened fire. (See ON - [text missing]
p.467 #4 In 1917 the British lost 3 Battleships in 20 minutes to enemy mines while they were trying to blast a path on the assault on Gallipoli. For special minesweeping arrangements for bombarding ships - see Chapter VII Section 7.
p.468 #1 These batteries were:- Barfleur, La Pernelle, Morsalines, Ozeville, Chateau De Courcy, Fontenay Sur Mer, Emondville, Maisy II, Maisy I, Pointe Du Hoc, Villerville, Beneville, Houlgate, Riva Bella, Oistreham, Colleville Sur Orne, Moulineaux, Mont Fleury, Ver Sur Mer, Arromanches I, Arromanches II, Longues, Vaux-Sur-Aure, and Le Grand Cloche, Le Havre.
p.468 #2 These were:- St. Martin De Varreville and Sallenelles.
p.468 #3 The pre-arranged time for opening fire was to be at first light on D-day, if Allied ships were within range of German batteries; if they were not yet within range, it was to be when the first ships came under fire of the German batteries. At night, ships within range of German batteries were not in great danger because; (1) The Germans could not aim visually in the darkness; (2) An elaborate Radar counter-measures plan was being executed which prevented German Radar from locating Allied vessels, see Chapter VIII, Sec.4 for details.
p.468 #4 See Reports of N.C.E.T.F. (Page 26) Vol.II ANCXF Report and N.C.W.T.F. (Page 68) Vol.III ANCXF Report.
p.469 #1 It will be recalled that the air force was simultaneously doing the same thing at every beach except Omaha.
p.469 #2 The British called these Forward Observers Bombardment (FOB).
p.471 #1 Report of NC Force 'O' contained in the ANCXF report Volume 3 Page 57.
p.471 #2 Experience in Sicily and Italy had indicated that the Germans paid particular attention to destroying spotting aircraft which were the highest of their list of priorities for counter action.
p.474 #1 In the Western Task Force Bombarding ships exclusive of craft standing off the beaches delivered the following quantity of naval fire, 15-in. 101 HC, 14-in. 508 A.P. 1490 H.C., 12-in. 163 A.P., 7.5-in. 1,200 H.C., 5.25 in. 65 A.P. 1,473 H.C., 5.38-in. 25,707 5.25-in. 118, 5.51-in. 376, 4-in. 3000, 656 H.C. 8-in. 168 A.P. 2,862 H.C. 6-in. 1,064 A.P. 5,414 H.C.
p.475 #1 Reference Admiralty Publications C.B. 3148 (Feb. '45) Gunnery Review - Normandy Bombardment Experience (June/Sept., 1944, Page 29).
p.476 #1 Reference Ibid, Page 28.
p.477 #1 For details of the bombardment of Cherbourg, see Reports of CTF 129 contained in Vol. III of ANCXF Report and also ANCXF War Diary for June 25, 1944.
p.477 #2 A misunderstanding arose regarding procedure in the mine clearance operation ahead of the bombarding force through the last minute change in plan of which the S.O. Minesweepers had not been informed.
p.479 #1 All materials in this section have been taken from the ANCXF (US) report on Naval Communications, Operation NEPTUNE.
p.479 #2 The location of enemy radar sites in the assault area as shown on sketch -.
p.479 #3 ONCO, Section XV.
p.483 #1 Except where otherwise noted the materials in this section were taken from the ANCXF (US) report on Naval Communications operation NEPTUNE. See Chapter II section 5 for the relation between these diversions and the General Cover Plan.
p.483 #2 See sketch - for the approximate position of diversionary forces at H minus 6 hours.
p.484 #1 Report of C in C Plymouth on Operation NEPTUNE Section II Page 30.
p.484 #2 "Window" are bits of metal foil, which are cut to a size "tuned" to the frequency of the Radar station being jammed, and which are dropped like confetti from an airplane or from a rocket projectile. They flutter earthward intercepting radar emissions and screen objects behind them.