Although the quick arrival of numerous U.S. destroyers in European waters in May 1917 and the subsequent arrival of relatively small numbers of U.S. Marines and U.S. Army troops in France in June 1917 improved Allied morale, the vast majority of U.S. troops had yet to arrive in France by the spring of 1918. With a large number of German troops on the Eastern Front freed up by the collapse of Czarist Russia, the Germans gambled on launching a massive offensive in France in the spring of 1918, hoping to knock Britain and France out of the war before significant numbers of U.S. reinforcements could arrive. Although the offensive gained considerable ground, casualties were extremely heavy on all sides, and the offensive ran out of steam before achieving its objective and the bloody stalemate on the Western Front resumed. At the same time, the Allied convoy effort, improved technology and anti-submarine tactics (including the use of air cover), along with reading the Germans’ message traffic, resulted in increasing ability for the Allies to get men and supplies through to Europe, and increasing losses of German U-boats. Because the British had broken the German navy submarine codes, the Allied strategy was generally to route convoys to avoid where they knew the U-boats were—to the growing frustration of the German navy.
Increasingly desperate to reverse the situation in the Atlantic, the Germans decided to convert several very large submarines that had been originally built as unarmed “merchant” submarines (in an attempt to run the highly effective British naval blockade) into U-cruisers (Unterseeboots-Kreuzer). Two of these submarines had made successful voyages to the United States in 1916 when the country was still officially neutral. Seven of the merchant cruisers had been built (and even larger ones were under construction) and five would be converted to U-cruisers. Armed with two 5.9-inch deck guns, two 20-inch torpedo tubes, 18 torpedoes, as well as mines, these were the largest (1,500 tons and a crew of six officers and 50 men), most heavily armed submarines in the world, and possessed enough range to reach the U.S. east coast and operate there for over a month.
U-151 departed Kiel, Germany, on 14 April 1918, destined for the United States, the first time a German submarine sailed to the western Atlantic intent on attacking shipping. The voyage was no secret to the Allies due to the broken codes, but this fact was successfully kept from the Germans. After laying mines, cutting cable, and sinking three fishing schooners, U-151 finally made her presence known (or so she thought) on 2 June. On that day, the submarine sank six ships and damaged two more over the course of about two hours. These included the liner SS Carolina, the freighters Winneconne and Texel, the schooner Isabel B. Wiley, and two other schooners, all with a combined crew and passengers of about 448 people. In all cases, U-151 fired warning shots and gave the crews time to abandon ship in an orderly fashion—women and children first in the case of Carolina—before sinking them with gunfire. The only fatalities were 13 dead (eight male passengers and five crewmen out of 218 passengers and 117 crew), when one of Carolina’s lifeboats capsized.
On 3 June, the tanker Herbert L. Pratt struck one of the mines previously laid by U-151 off the Delaware Capes and sank, although it was later raised. On 9 June, U-151 stopped the Norwegian cargo ship Vindeggan off Cape Hatteras and set scuttling charges after transferring a very valuable cargo of 70 tons of copper ingots off the vessel. On 14 June, U-151 sank the Norwegian barque Samoa, also with no casualties.
Up to this point, U-151’s actions had displayed a civility that by this time was absent on the eastern side of the Atlantic, but on 18 June, the submarine sank the British flag liner SS Dwinsk and loitered near the seven lifeboats in order to ambush any ships coming to the rescue. The auxiliary cruiser and troopship USS Von Steuben (ID-3017) initially took the bait. Von Steuben was originally the German passenger liner SS Kronprinz Wilhelm, which had been armed and operated as raider, sinking or capturing 15 ships before she was interred in the United States in 1915 when she ran short of coal. Converted to an auxiliary cruiser after the United States entered the war, Von Steuben had been one of the first ships to respond to the 7 December 1917 disaster in Halifax, Nova Scotia, when an ammunition ship exploded in the harbor, killing over 2,000 people.
U-151 fired torpedoes at Von Steuben, which were sighted by alert lookouts, and the Von Steuben’s skipper, Captain Yates Stirling, Jr., avoided the torpedoes with the unorthodox maneuver of a hard starboard turn with engines at full astern (normal procedure was to try to turn away from the torpedo and possibly outrun it). After the torpedoes missed, Von Steuben responded with a depth charge attack on U-151 that actually did inflict some damage on the sub. For his actions, Captain Stirling was awarded both the Navy Cross and the French Legion of honor. In the meantime, the captain of the Dwinsk ordered all of those in the lifeboats to lie low so as not to draw any other ships into the trap. Eventually, six of Dwinsk’s lifeboats made it to safety, but the seventh, with 22 aboard, was never seen again. The Von Steuben went on to make nine Atlantic crossings, carrying about 2,000 troops each time. U-151 returned to Kiel on 20 July after a 94-day cruise that covered 12,500 miles. The commanding officer reported sinking 23 ships totaling 61,000 tons, of which three were later salvaged, and four more were sunk by mines laid by the submarine.
On 15 June, U-156, sister of U-151, under the command of Korvettenkäpitan Richard Feldt, deployed from Kiel. She arrived off New York harbor and laid a string of mines in the shipping lanes off Long Island just east of the Fire Island Lightship. On 19 July, the armored cruiser USS San Diego (Armored Cruiser No. 6—former USS California) suffered a large explosion about 10 miles southeast of Fire Island, with damage severe enough that she sank. No torpedoes had been sighted nor had any other evidence of a submarine. San Diego had previously suffered a damaging boiler explosion in January 1915, but she was probably sunk by one of the mines laid by U-156. The explosion on the port side flooded the port engine room and warped the bulkhead and watertight door, resulting in flooding of the Number 8 fireroom. Unfortunately, progressive flooding could not be controlled and she sank in 28 minutes. Of her crew of 80 officers, 745 enlisted sailors, and 64 Marines, two were killed instantly and four more died later. Two crewmen were awarded the Medal of Honor for their actions during the sinking. At 14,000 tons, 500 feet long and armed with four 8-inch guns and 14 6-inch guns, San Diego was the largest U.S. warship to be sunk in the war. The ship sank in relatively shallow 110 feet of water, and her wreck has been extensively pillaged by divers. However, more sport divers have died on the wreck site than crewmembers were killed in the actual sinking.
On 21 July, U-156 surfaced just off the Cape Cod town of Orleans and opened fire on the tugboat Perth Amboy, which was towing three barges (some accounts say four). The tug was quickly in sinking condition and U-156 turned her attention to the barges and opened fire. Because of their low silhouettes, a number of shells went long and impacted in a marshy area near Orleans, although some reports say some structures were damaged. The shelling caused startled bathers to flee the water, while at least one townsperson opened fire on the U-boat with a shotgun, which, of course, did nothing. There were at least some women and children aboard the tug and barges, so a surfboat from Station 40 of the U.S. Life-Saving Service (later part of the U.S. Coast Guard) valiantly rowed out under fire and succeeded in rescuing all 32 people from the tug and barges. Townspeople were immediately on the phone to the Boston Globe and to the Naval Air Station at Chatham, Massachusetts. The paper provided an event-by-event reporting, which later became an early example of a media frenzy, and an end result of numerous contradictory reports, such that it is difficult to tell what really happened. The incident served to further fuel the wild rumors and outright hysteria that swept the U.S. east coast during this period, such as reports that German submarines were equipped with aircraft, resulting in anti-aircraft defenses being set up in New York City and the gold dome of Massachusetts’ statehouse being painted over so it could not be used as a navigational landmark.
After initially being incredulous that a submarine was that close in to the shore, NAS Chatham quickly launched at least four (and maybe nine—reports vary) Curtis HS-1L flying boats and R-9 seaplanes. (As an aside, over 600 of the HS-1Ls were built and deployed in the space of a little over a year, an example of U.S. industrial might, once mobilized). A small flotilla of U.S. Navy submarine chasers sortied from Provincetown. The first aircraft caught the submarine by surprise, but a release lever failed to work on the first aircraft, and bombs failed to explode from several others. Some of the aircraft hit close enough to the submarine that, had the bombs worked properly, the submarine would at least have been damaged. In frustration, one pilot claimed to have thrown a wrench at the submarine. The sub quickly submerged, then changed her mind and came back up, apparently intending to duke it out on the surface using shrapnel rounds against the aircraft. (It should be noted that only one submarine was confirmed sunk by air attack during World War I, although air cover was very effective at disrupting U-boat attacks on convoys and no ships were lost in convoys that had air cover).
As the attempted air attacks went on for some time, as did the equally fruitless submarine air defense, the flotilla of sub chasers turned back, apparently deciding that discretion was the better part of valor since the submarine’s 5.9-inch guns were much more capable than their own 3-inch guns. The result, however, was that the aircraft and the life-saving boat garnered the glory, which was probably appropriate, and the U.S. Navy did not. U-156 was on the surface for over 90 minutes and fired almost 150 rounds. In fact, the U.S. Navy took a public beating from politicians and public because despite the hugely expensive naval expansion act of 1916, intended to create a Navy equal to that of any of the world, the Navy could not seem to hunt down and deal with one solitary submarine. Navy leaders, however, quickly reached the conclusion that the U-cruiser operations were just a high-visibility attempt to divert Allied assets from the main effort, i.e., to get as many American troops across the Atlantic as fast as possible in order to regain ground lost to the spring German land offensive.
Following the circus off Orleans, U-156 went into the Gulf of Maine and ran amok amongst the U.S. fishing fleet, sinking 21 of them herself, while manning and arming a captured Canadian trawler that sank seven more. In the end, U-156 sank 34 ships for a total 33,500 tons and, like U-151, had operated with effective impunity off the U.S. east coast for a combined three-month period. For the most part, both U-151 and U-156 had made an effort to rescue survivors, and their very large hauling capacity and lack of effective opposition gave them the luxury of keeping rescued crewmembers on board until they could be off-loaded safely. However, on 25 September, while attempting to return to Germany, U-156 struck a mine in the recently laid North Sea mine barrage (mostly laid by the U.S. Navy) and sank with all 77 hands. The 100,000 or so mines laid in the North Sea barrage in the summer of 1918 accounted for about six German submarines lost, but was a big morale buster in the German navy. (More on the North Sea mine barrage in a future H-gram.)
By the time U-156 departed the western Atlantic, three more U-cruisers had arrived in waters off the U.S. These were the U-140, U-117, and U-155. U-155 was the former merchant submarine Deutschland, which had made two trips to the United States in 1916 before the country entered the war and before it was converted to a heavily armed U-cruiser. U-140 was of a new class designed from the keel up to be armed U-cruisers, the largest submarines in the world. U-117 was a long-range minelaying submarine.
Like the first two U-cruisers, U-140 was having a field day off the U.S. east coast until she attacked the Brazilian passenger liner Uberaba on 10 August. Unlike most ships, Uberaba attempted to flee when the submarine surfaced to fire warning shots and, as a result, came under direct fire from the U-boat in a running battle and took some hits. Among the 250 passengers (including women and children) aboard the ship were 100 U.S. Navy personnel, many of whom pitched in to stoke coal in order to outrun the U-boat. Nevertheless, Uberaba got off a distress call, which was answered so quickly by the destroyer USS Stringham (DD-83) that U-140 was caught by surprise and barely managed to submerge. Stringham dropped 15 depth charges and damaged the submarine badly enough that U-140 had to abort her mission and return to Germany in September 1918, having sunk only seven ships. Stringham would go on to earn nine battle stars during World War II, mostly as a fast personnel transport (APD-9).
,After reaching the U.S. east coast about 9 August 1918, U-117 did score a noteworthy success with her mines. On 29 September, the battleship USS Minnesota (BB-22) struck one of U-117’s mines off Fenwick Island, Delaware, which resulted in extensive damage that knocked Minnesota out of the rest of the war, but caused no casualties. It could have been worse, had not Vice Admiral Albert W. Grant (commander of Battleship Force 1) not initiated his own program to have ships under his command reinforce their bulkheads (an action that spared Minnesota the damage that had caused the loss of San Diego). Minnesota was the largest U.S. warship significantly damaged during World War I. (The battleship had been under the command of then-Commander William Sims, unusual at the time (or any time), thanks to political influence of Theodore Roosevelt. Sims was actually relieved of command of Minnesota in 1911 for making public pro-British statements before that was considered socially acceptable in the U.S. Navy.) The Fletcher-class destroyer named after Vice Admiral Grant (DD-649) fought at the Battle of Surigao Strait during the larger Battle of Leyte Gulf in October 1944. While conducting a night torpedo attack against the Japanese battleship force, she got caught in the cross-fire and was hit 22 times; many of the hits were 6-inch shells from U.S. cruisers. Heavily damaged, with 38 killed and 104 wounded, her crew nevertheless saved their ship despite encountering a typhoon.
When World War I ended, three more U-cruisers were en route the western Atlantic, but they turned back and were surrendered to the Allied forces along with the entire German navy. Six U-boats would end up in U.S. hands, one of which (UC-97) was commanded by Lieutenant Charles A Lockwood (future vice admiral in charge of U.S. submarines in the Pacific during World War II) and is now on the bottom of Lake Michigan. (More on that story in a future H-gram.)
(Sources include America’s U-boats: Terror Trophies of WWI by Chris Dubbs , 2014, The Kaiser’s Lost Kreuzer: A History of U-156 and Germany’s Long-Range Submarine Campaign Against North America, 1918 by Paul N. Hodos, 2017, and NHHC Dictionary of American Fighting Ships entries.)
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