Military history


Thirteen of the twenty-nine boats of the April group that reached the Americas were Type IXs, ten of which had made a prior patrol to that area.

The first IX to sail was U-125, a Type C commanded by Ulrich Folkers, who had made a disappointing maiden patrol off Cape Hatteras in January. Dönitz assigned him to virgin territory: an area in the Caribbean off southwest Cuba, at the southern approaches to the Yucatan Channel, which separates Cuba and the Yucatan area of Mexico. Outbound from France, Folkers sank by torpedo and gun a lone 5,100-ton American freighter in mid-ocean. Upon reaching his area in early May, he found heavy, unescorted shipping plying between the Panama Canal Zone and the Gulf of Mexico. In the ensuing sixteen days, May 3 to May 18, Folkers sank by torpedo and/or gun eight more ships, including two tankers, the 8,900-ton American Mercury Sun, and the 12,000-ton Canadian Calgarolite, bringing his total bag to nine confirmed ships for 47,000 tons. Discounting the two “unknowns” Hardegen claimed on his first Drumbeat patrol, it was the most fruitful voyage by any U-boat in American waters to date. Proudly reporting this bonanza and suggesting that other boats should patrol the area, Folkers returned directly to France without refueling, completing the round trip in seventy-one days.

The next two boats to sail were the new extended-range Type LXC sister ships, U-506 and U-507. These and von Mannstein’s Type VII U-753 were to launch the U-boat campaign in the Gulf of Mexico, where it was believed, correctly, ASW measures were weak. Both IXs were to enter the gulf via the Old Bahama Channel (north of Cuba) and the Straits of Florida. Upon reaching the Old Bahama Channel on April 30, Harro Schacht, age thirty-four, in U-507, found and sank the lone 2,900-ton American tanker Federal by gun. Trailing by several days, on May 3, Erich Wtirdemann, age twenty-eight, in U-506, shot a torpedo to sink the 600-ton Nicaraguan freighter Sama in the Florida Straits.

Dönitz had directed both LXs to proceed northwest across the gulf to the mouth of the Mississippi River. It was assumed, correctly, that the area would be swarming with ships. Several surprise sinkings might close the Mississippi to traffic, a worthwhile objective, but not without real danger for these big boats: the water at the delta was muddy and quite shallow and the currents were extremely tricky.

Protection of shipping in the Gulf of Mexico and Yucatan Channel was the responsibility of the newly established Gulf Sea Frontier, commanded by Russell S. Crenshaw, who had set up headquarters in Key West, terminus of the East Coast Bucket Brigade and other convoys.* Like Adolphus Andrews, his counterpart on the East Coast, Crenshaw had only slim resources: two four-stack destroyers (Noa, Dahlgren), nine 165-foot and 125-foot Coast Guard cutters, five large converted yachts, and about thirty-five Army, Navy, and Coast Guard aircraft. Astonishingly, two of these aircraft on hurriedly mounted ASW patrols scored near misses on both U-506 and U-507. Würdemann in U-506 reported heavy damage to one of his two stern tubes. Schacht in U-507 reported damage to his starboard bow plane and the loss of two tons of fuel oil, apparently from a ruptured tank.

Schacht in U-507 sank the first ship inside the gulf, the 2,700-ton American freighter Norlindo. Hit by a single torpedo, she sank stern first in three minutes. Schacht gave the survivors forty packs of cigarettes, a cake adorned with French writing, crackers, matches, water, and ten gallons of time pulp made from fresh times. “Sorry we can’t help you [further],” Schacht said in perfect English, according to the survivors, “Hope you get ashore okay.”

The next night, May 5, Schacht sank two American tankers by torpedoes. The first was the 5,100-ton Munger T. Ball, fully loaded with gasoline, which burst into flames. Thirty-seven of forty-one crewmen perished. The second was the 7,000-ton Joseph M. Cudahy, which radioed a report of the Ball sinking, adding unwisely and unnecessarily, “Nine miles away.” Upon hearing that, Schacht immediately searched for, found, and chased Cudahy. His first torpedo missed, but the second hit and she sank. Twenty-seven of thirty-seven crewmen died.

Later that night, the U-507 crew downloaded torpedoes from the topside canisters. While doing so, the restraining gear broke and a torpedo slid uncontrolled into the bow compartment. On its downward path, it struck and gashed open the arm of a radioman, a severe and excruciatingly painful injury. Schacht reported the injury to Kerneval and the fact that he had no painkillers. Kerneval arranged a rendezvous with Würdemann in U-506, who had morphine; however, the boats failed to meet. Kerneval arranged a second rendezvous, which also failed, then a third, likewise fruitless. The sinkings and the numerous radio transmissions to set up the rendezvous attracted swarms of Army, Navy, and Coast Guard aircraft and led to stringent shipping controls in the Gulf Sea Frontier, similar to those in effect in the Eastern Sea Frontier.

Schacht gave up trying to find Würdemann and resumed his course to the Mississippi River. He put the injured crewman in an officer’s bunk, dressed his festering wound, and gave him sleeping pills. On May 6, he came upon the 6,800-ton American freighter Alcoa Puritan, loaded with bauxite. Schacht missed with one torpedo, attacked with his 4.1” deck gun, then finished off the ship with a torpedo.* On the day after that, he sank the 3,100-ton Honduran freighter Ontario by gun. A day later still, May 8, he sank the 2,400-ton Norwegian freighter Torny with a single torpedo. Two crew members died; a Navy seaplane rescued the twenty-four survivors.

Both U-506 and U-507, on about May 10, finally closed on the mouth of the Mississippi River. Würdemann in U-506 mounted the first attack. He shot four torpedoes at the old (1920) 7,000-ton American tanker Aurora, sailing in ballast. After the crew abandoned ship, Würdemann surfaced and raked the ship with his 4.1” deck gun. He claimed that Aurora sank in flames, but in fact, a Coast Guard vessel towed her into Burrwood, Louisiana, and she ultimately returned to service.

Würdemann and Schacht patrolled off the mouth of the Mississippi River for ten days, May 11 to May 20. In a notable series of torpedo attacks, Würdemann in U-506 hit seven different American ships, sinking five: the tankers Gulfpenn, 8,900 tons (90,000 barrels of fuel oil); David McKelvy, 6,800 tons (80,000 barrels of fuel oil); Gulfoil, 5,200 tons (petroleum products); Halo, 7,000 tons*; and the freighter Heredia, 4,700 tons (bananas, coffee). Crew losses were heavy: thirteen of thirty-eight on Gulfpenn, seventeen on McKelvy, twenty-one on Gulfoil, all but three on Halo, and thirty-eight of sixty7 one on Heredia. The damaged ships were the tankers William C. McTarnahan and Sun, sailing in ballast. Bedeviled by nine torpedo misses, failures, or malfunctions, including two circular runners, Schacht in U-507 sank two ships: the 10,700-ton American tanker Virginia by two torpedoes, and the 4,150-ton Honduran freighter Amapala by gunfire, boarding, and scuttling. Twenty-seven of forty-one crew members on Virginia perished.

Having expended all torpedoes, U-506 and U-507 headed home by way of the Straits of Florida. On the way back, Würdemann in U-506 sank two British freighters by gun east of Florida, raising his confirmed score to eight ships (four tankers) for about 40,000 tons sunk plus damage to three big tankers. Schacht’s total was nine confirmed ships (four tankers) sunk for about 45,000 tons. According to Homer Hickam in his book Torpedo Junction, over 200 crewmen in these seventeen lost ships (eight tankers) were killed in the sinkings or later died in the water or in lifeboats or rafts.

As noted earlier, the single VII of the April group assigned to the Gulf of Mexico was the U-753, commanded by thirty-four-year-old Alfred Manhardt von Mannstein. He had made one prior patrol in the defense of Norway, cut short when U-753 was rammed and severely damaged topside by a British “destroyer.” The voyage to America was thus U-753’s first full-scale patrol.

Von Mannstein operated in the Gulf of Mexico for about two weeks, May 19 to June 1, in the wakes of U-506 and U-507. Inbound to the gulf via the Straits of Florida on May 19, he spotted a convoy off the western tip of Cuba. He boldly swung around to close and shoot submerged, but the boat suddenly rose and a merchant ship rammed her, mangling the deck gun, which the crew later dismounted and stowed below. This mishap thwarted the attack on the convoy, but over the next several days he shot five torpedoes to sink the 7,200-ton American freighter George Calvert and attacked a 300-ton British sailing schooner with a cargo of lumber, E. P. Theriault, by gun. He boarded her and set scuttling charges, but Theriault survived.

Continuing this relentlessly aggressive patrol, von Mannstein had mixed success. An attack on an Erie-class gunboat failed: one torpedo missed, and another ran hot in the tube and had to be ejected. Proceeding northwest to the mouth of the Mississippi River, von Mannstein attacked two big tankers, May 25 to 27. He damaged the 6,600-ton Norwegian Haakon Hauan and sank her sister ship, the 6,600-ton Hamlet, expending five torpedoes. On June 1, von Mannstein left via the Florida Straits, having sunk in this first Type VII foray into the Gulf of Mexico two confirmed ships (one tanker) for about 13,800 tons.

While U-753 was homebound in the Bay of Biscay in the late afternoon of June 23, a Whitley of Coastal Command Squadron 58, piloted by W. Jones, found and depth-charged her. The initial attack was skillful: the explosions knocked out U-753’s diesels and rendered her incapable of diving. The British failed to follow up the attack and, although “badly damaged,” U-753 managed to survive. France-based German aircraft and motor launches found U-753 the next morning and escorted her into La Pallice, where she remained out of action for the next three months.

This calamity, atop the British aircraft attacks on other boats in June, persuaded Dönitz on June 24 to change procedures for crossing the Bay of Biscay. Until then, the orders were fairly loose, leaving tactics up to the skippers. Most preferred to run on the surface day and night to get across this increasingly dangerous area as quickly as possible, relying in daytime on lookouts to spot enemy aircraft early enough to dive to safety, and feeling more or less immune to attack at night. Since the radar-equipped Leigh Light Wellingtons rendered surface travel risky day or night, Dönitz decreed specifically that all U-boats were to cross the Bay of Biscay submerged, surfacing only briefly at night to recharge their batteries and to refresh the air in the boat.

This was not a welcome change inasmuch as the boats could barely log more than a hundred miles a day, and this greatly prolonged the crossing and reduced time in the operating areas, but it was intended to be only temporary, pending the arrival of the Metox radar detectors, or FuMBs, and much-improved antiaircraft weaponry, including twin 37mm and 20mm rapid-fire guns. With Metox and these more powerful weapons, Dönitz believed that a U-boat could successfully fight it out with an enemy plane in daytime, hence travel on the surface during the day could be resumed.

Of the three older, shorter-range Type IXBs which set off for the United States East Coast in April, two made promising starts. Werner Winter in U-103, who refueled from the U-tanker U-459, sank a 6,000-ton British freighter in mid-Atlantic May 5. The same day, Hermann Rasch in U-106 sank an 8,000-ton Canadian freighter. But after that it was all downhill. Patrolling offshore from Cape Hatteras to Florida, neither boat saw anything for days on end. Similarly, the third IXB, U-107, commanded by Harald Gelhaus, who arrived off Cape Hatteras a week later, saw nothing. All three U-boats felt the effect of the new Key West-Norfolk-Key West convoy system.

The absence of East Coast traffic and the great successes of Folkers, Schacht, and Wiirdemann in the Yucatan Channel and the Gulf of Mexico prompted Dönitz to shift these three Type IXBs to those areas. To do so, it was necessary to arrange for Rasch’s U-106 and Gelhaus’s U-107 to be refueled homebound by U-459, which was to make a rapid turnaround in France.

Winter in U-103 and Rasch in U-106 led the way. Winter went south through the Windward Passage to replace Folkers in the southern approaches to the Yucatan Channel; Rasch went west through the Straits of Florida to replace Schacht and Wiirdemann in the Gulf of Mexico. As related, at this same time four Type VIIs entered the Caribbean Sea and von Mannstein in the Type VII U-753 also patrolled in the Gulf of Mexico off the mouth of the Mississippi River.

Both U-103 and U-106 found good hunting. Patrolling south of the Yucatan Channel, May 17 to May 28, Winter in U-103 sank eight ships for 36,200 tons, bringing his bag on this patrol to nine ships for 42,200 tons. His victims included two American tankers: Sam Q. Brown, 6,600 tons, and New Jersey, 6,400 tons. Homer Hickam wrote that after sinking the 5,000-ton American freighter Ogontz, Winter apologized to her captain (“Sorry … but this is war”), personally medicated one survivor, and directed that the lifeboats be stocked with cigarettes and food.

Patrolling north of the Yucatan Channel in the Gulf of Mexico for an equal number of days, May 21 to June 1, Rasch in U-106 missed a huge whale-factory ship with two torpedoes but sank four ships for 21,200 tons and damaged a 4,600-ton American freighter, bringing his sinkings on this patrol to five ships for 29,000 tons. His victims also included two tankers, the Mexican Faja de Oro, 6,100 tons, and the American Carabulle, 5,000 tons, sunk by 193 rounds from his 4.1” deck gun and two torpedoes. Twenty-two of forty crew members on Carabulle perished. Homebound, both U-103 and U-106 refueled as planned from U-459, which sailed on her second resupply mission June 6 after three weeks of voyage repairs. Counting past claims and sinkings, Winter qualified for a Ritterkreuz, which was awarded while he was still at sea.* Upon his return to France, he left the boat to command Combat Flotilla 1.

Lagging behind his sister ships, Gelhaus in U-107 went south into the Caribbean via the Windward Passage on May 29. That night he sank a 2,600-ton British freighter, then proceeded to the area south of the Yucatan Channel, replacing Winter in U-103. In the ensuing ten days, June 1 to June 10, he sank four freighters for 14,200 tons. Homebound, in the mid-Atlantic, he sank the impressive 10,000-ton Dutch freighter Jagersfontein, bringing his bag to six freighters for 27,000 tons. Then he refueled from U-459, as planned.

In all, these three Type IXBs, U-103, U-106, and U-107, sank twenty ships for 98,300 tons on patrols of sixty-nine, seventy-six, and eighty-two days, respectively. These successes were directly attributable to the availability of U-459 for refueling. Without refueling, none of these shorter-range IXBs could have carried out extended patrols in the Gulf of Mexico or the Yucatan Channel.

Altogether, the six Type IX captains who sailed in April (Folkers, Gelhaus, Rash, Schacht, Winter, Wiirdemann) sank forty-six ships (fourteen tankers) for 230,000 tons. This was an average of 7.7 ships for 38,333 tons per boat per patrol.

In response to this slaughter, Admiral King named the experienced U-boat hunter James L. Kauffman, who had been Commander of Naval Forces, Iceland, to replace Crenshaw. On June 17 Kauffman shifted the headquarters of the Gulf Sea Frontier from Key West to a more elaborate facility in Miami. At the same time, Hap Arnold directed First Air Force commander Follett Bradley to establish an ASW Gulf Task Force to serve under Kauffman’s direction, with headquarters in Miami. Composed initially of twenty B-18 bombers and two squadrons of observation planes, the Gulf Task Force was activated about June 1. It was reinforced by eight B-17 bombers and two observation squadrons from Third Air Force training units in Florida and Louisiana, and by the Civil Air Patrol.

In her study of U-boats in the Gulf of Mexico,* Melanie Wiggins writes that in the wake of this May slaughter of shipping, local officials resorted to stern measures. Convinced of the truth of rumors that the U-boat skippers obtained help from “Axis aliens” living along the coast, American and Mexican authorities rounded up suspects and spirited them away (a story that needs further airing). Notwithstanding the Navy’s doubts of its value and the dangers to motorists and truckers, on June 1 American officials dimmed out Galveston and other areas along the coastline.

This slaughter in the gulf drew vigorous demands for better protection of shipping from oil companies, merchant seamen, and, behind the scenes, the British. Rising in defence of the Navy, Congressman Carl Vinson, Chairman of the House Naval Affairs Committee, declared on June 6 that American ASW forces had “passed growing pains” and were “well established and functioning effectively,” and that his committee was fully confident that Axis submarines would be defeated. “Critics should remember,” he said, “that the British have had three years [sic] experience in coping with the U-boat problem and that the British Isles [where the problem had been largely overcome] would fit comfortably into the Gulf of Mexico.”

Four long-range Type IXs patrolled the southern Caribbean from Trinidad to the Panama Canal. Three of the four were directed to attack shipping off the canal, but when B-dienst predicted heavy tanker traffic off Trinidad, that mission was canceled. All four boats patrolled in the eastern Caribbean near Trinidad and the north coast of Venezuela.

The first to sail was Jürgen Wattenberg in the IXC U-162, who had been forced to abort his first patrol to the Americas with mechanical defects. At forty-two years of age, Wattenburg (crew of 1921) was the oldest active skipper of an attack boat in the Atlantic U-boat force. Earlier in the war he had served on the “pocket” battleship Admiral Graf Spee, but after she was scuttled, he had made his way back to Germany.

Perhaps eager to avenge the humiliating loss of that ship, Wattenburg conducted a notably aggressive patrol in U-162. In a nineteen-day period, April 30 to May 18, he sank eight confirmed ships by torpedo and gun for 47,000 tons plus a 119-ton American sailing schooner, Florence M. Douglas. His sinkings included four tankers.* One of his victims, the 6,700-ton Brazilian freighter Parnahyba, moved the Brazilian government one step closer to a declaration of war against Germany. The sailing schooner yielded three live pigs. The Germans ate two but adopted the third, “Douglas,” as a mascot, which they presented to flotilla commander Viktor Schütze when they reached France.

The return trip of U-162 was also memorable. By the night of June 8, when Wattenburg reached the western fringes of the Bay of Biscay, RAF Coastal Command ASW patrols were intense. One of these aircraft equipped with meter-wavelength ASV radar caught U-162 on the surface. Wattenburg crash-dived. The bombs or depth charges caught the boat at 80 or 90 feet but did no serious damage. Still, it was a new and disconcerting experience for the crew, another of the air attacks that led to Dönitz’s specific order of June 24 to cross the Bay of Biscay submerged.

The other three IXs arrived in the Trinidad area about the time Wattenburg in U-162 was concluding his patrol. Two of the three skippers, Werner Hartenstein in U-156 and Jürgen von Rosenstiel in U-502, had opened the U-boat war in the Caribbean in February; the other, Adolf-Cornelius Piening in U-155, had made one patrol to Cape Hatteras.

Piening in the IXC U-155 hunted west of Trinidad toward the island of Los Testigos, where the shipping was so dense that he and his crew scarcely slept. Notwithstanding a double miss on a tanker, in seventeen days, May 14 to May 30, he sank by torpedo seven confirmed ships for 33,000 tons and probably damaged another. His victims included two tankers: the 8,100-ton British San Victorio (benzine and paraffin) and the 7,800-ton Panamanian Sylvan Arrow. The loss of life on San Victorio was brutal: Only one man of fifty-four survived. Intending to close the coast of Venezuela to raid shipping with his deck gun, Piening was thwarted by the failure of his gyrocompass. He returned directly to France without refueling, a round trip of merely fifty-six days.

Werner Hartenstein in U-156 had even better success in Atlantic waters east of Trinidad. In a six-day period from May 13, he sank five freighters for 25,600 tons and damaged the 8,000-ton British tanker San Eliseo. However, Hartenstein’s rich harvest was interrupted by a message from Dönitz assigning him to a special mission.

From press reports and other sources, Hitler had formed the incorrect impression that the United States intended to invade and capture the Vichy island of Martinique and the naval vessels there, including the old aircraft carrier Béarn. Unable to persuade the Vichy government to scuttle the warships, and unaware that pressure from Washington already had persuaded the Vichy French to immobilize them, Hitler directed Raeder to send U-boats to Martinique to thwart an invasion and/or to destroy any Vichy warships—Béarn in particular—which might attempt to leave the harbor to join the Free French Navy serving with Allied naval forces.

Inasmuch as Hartenstein in U-156 had earlier sneaked into Fort-de-France (to land an injured officer) and fortuitously had brought along updated charts of Martinique, Dönitz assigned him to lead the mission. He was reinforced by one other boat, U-69, a Type VII commanded by Ulrich Gräf, who had earlier refueled from U-459 and come south to the Caribbean.

Hartenstein and Gräf took up stations off Martinique on May 20. The next day Hartenstein sank a 1,700-ton Dominican freighter and Gräf sank a 1,900-ton Canadian freighter. Upon receiving the sinking reports, Dönitz reminded the skippers tartly that their “main task” was to attack American warships or Vichy warships leaving Fort-de-France. Four days later, May 25, Hartenstein hit the four-stack American destroyer Blakeley. The blast blew off sixty feet of her bow, killing six and wounding twenty-one crewmen. Astonishingly, Blakeley managed to limp into Fort-de-France. Dönitz denied a request from Hartenstein to penetrate the harbor to finish off the destroyer.*

The hit on Blakeley caused uproars in Washington and Vichy. Perhaps as a result, the Vichy French government disclosed to Berlin that its warships at Martinique had been immobilized and posed no threat to either the Allies or the Axis. Even so, Hartenstein and Gräf remained off the island for another week. During that time Hartenstein sank two more ships, including the 6,000-ton Brazilian Alagrete, but he paid a heavy price. An American Catalina, apparently equipped with meter-wavelength ASV radar, found and bombed U-156. The blast cracked two main ballast tanks and a fuel ballast tank and knocked out all the hydrophone gear. Reporting this mishap, Hartenstein aborted the patrol and complained of the nearly unendurable tropical heat, made all the worse because the constant pressure of American ASW forces had forced him to remain submerged 121 hours out of 168 hours during the previous seven days.

In the meantime, the fourth Type IX in the southern Caribbean, U-502, commanded by Jürgen von Rosenstiel, had been patrolling farther westward, near the islands of Curaçao and Aruba, where she had done well on her first Caribbean patrol. This time the hunting was poor. In two weeks von Rosenstiel sank but one ship, the 5,000-ton Brazilian Goncalves Dias. In early June, however, when Dönitz shifted U-502 easterly to the Trinidad area, her successes improved dramatically. In the two-week period, June 2 to June 15, von Rosenstiel sank six confirmed ships for 31,300 tons, bringing his score for the patrol to an impressive eight ships for 41,200 tons. His victims included two American tankers: M. F. Elliott, 6,900 tons, and F. K. Lane, 6,600 tons.

Upon departing Martinique, Hartenstein in U-156 teamed up with von Rosenstiel in U-502 for the return voyage to France. On June 22 Hartenstein, who had conducted a largely stationary patrol, transferred fuel oil to von Rosenstiel, who had roamed considerably. The following day, von Rosenstiel in U-502 sighted the 4,600-ton British freighter Willimantic, sailing alone, but he had neither torpedoes nor deck gun ammunition. Responding to the sighting report, Hartenstein in U-156 found and sank Willimantic by gun and took her captain prisoner. This sinking raised Hartenstein’s bag for the patrol to an even more impressive nine freighters and a sailing vessel sunk for 40,000 tons, plus damage to the 8,000-ton British tanker San Eliseo and the American destroyer Blakeley.

Hartenstein and Rosenstiel reached the western fringes of the Bay of Biscay in early July. The Wellingtons of Coastal Command Squadron 172, fitted with ASV radar and Leigh Lights, had been, patrolling the bay for about one month. In the early hours of July 5, a Wellington, commanded by Pilot Officer Wiley B. Howell, an American serving in the RAF, picked up Rosenstiel’s U-502 and straddled her with four shallow-set 250-pound depth charges. Nothing more was ever heard from U-502. There were no survivors of this first successful sinking by a Leigh Light Wellington;

In all, the four IXs patrolling the southwest Atlantic and the Caribbean also achieved very good results. They sank thirty-four confirmed ships (eight tankers) for about 164,000 tons, an average of 8.5 ships for 41,000 tons per boat per patrol.

The last three of the thirteen IXs to sail in April drew a special mission. Operating loosely as a group, they were to attack Allied shipping in the area of the Brazilian island of Fernando de Noronha, 250 miles northeast of Natal, at the “bulge” in Brazil. These skippers were Ritterkreuz holder Ernst Bauer in U-126, Ulrich Heyse in U-128, and Albrecht Achilles in U-161. All had made prior patrols to the Americas. Each boat carried twenty-three torpedoes: fifteen electrics internally and eight airs in topside canisters.

While en route to this distant area, on May 11, Heyse in the IXC U-128 came upon a large northbound convoy, Sierra Leone 109, composed of thirty-one ships guarded by only four escorts. The escorts picked up Heyse’s contact report by Huff Duff, chased down the bearing, and drove him off and down. Three delivered depth-charge attacks. Two of the escorts, the sloops Landguard (ex-American Coast Guard cutter Shoshone) and Hastings, incurred “major engine defects” from their own depth-charge explosions. As a consequence, Landguard had to be taken in tow by a merchant ship, leaving only three escorts to protect the convoy.

The next day, May 12, Heyse brought up Bauer in U-126 and Achilles in U-161. After dark, Heyse in U-128 attacked, firing four bow torpedoes at two ships. He reported several hits, but only one vessel, the 3,500-ton British freighter Denmark (loaded with iron ore) went down. Exceptionally aggressive action by the escorts, including Landguard, who slipped her tow, held all three U-boats at bay. Under orders to conserve fuel and torpedoes for the special mission, the three boats did not press the attack on the convoy.

Arriving in the area of Fernando de Noronha, the task force could find no shipping. Therefore in early June Dönitz ordered the pack to rake northwesterly along the coast of South America to Trinidad. Cruising that area over the next thirty days, Bauer in U-126exceeded his earlier, spectacular patrol to the Windward Passage by sinking five confirmed ships for 41,500 tons and two sailing ships, plus damage to the 7,100-ton American tanker Gulfbelle, which fought back spiritedly with her guns. His sinkings included two Norwegian tankers: Höegh Giant, 11,000 tons, and Leiv Eiriksson, 10,000 tons. In an adjacent area, east of Trinidad, in the period from June 8 to 28, Heyse in U-128 sank four more ships for 32,000 tons, and damaged the 5,700-ton American freighter Steel Engineer. His victims also included two Norwegian tankers: South Africa, 9,200 tons, and Andrea Brövig, 10,200 tons.* Achilles in U-161 found the weather and the hunting poor. Near Trinidad, where he achieved fame on his first patrol, he found a convoy on June 14 but managed to sink only one 8,000-ton freighter, Scottsburg, and in return was rammed.

After makeshift repairs, Achilles went west to the Panama Canal area, where he sank a 35-ton American sailing vessel, Cheerio, by gun and torpedoed a 3,300-ton freighter at dockside in Puerto Limon, Costa Rica. However, the freighter was later salvaged. Homebound, he attacked a military convoy and sank a ship loaded with important cargo. Also homebound, Bauer in U-126 found a “heavily smoking” northbound convoy west of the Bay of Biscay, but Dönitz suspected it was a U-boat “trap” and refused Bauer permission to attack.

All three boats of this special task force refueled in July on the way back to France. Bauer in U-126 arrived on July 22, having sunk seven confirmed ships (two tankers) for about 42,000 tons. Heyse in U-128 arrived on July 25, having sunk five confirmed ships (two tankers) for about 36,000 tons. Achilles arrived on August 7, completing a record patrol of 102 days, during which he sank two confirmed freighters for 14,200 tons, and damaged another of 3,300 tons at dockside in Costa Rica.

The returns of the thirteen Type IXs sailing in April to the Gulf of Mexico and the Caribbean shattered all existing records. Including the sailing vessels, they sank ninety-five confirmed ships (twenty-six tankers) for 482,843 tons, an average of 7.3 ships of about 37,141 tons sunk per boat per patrol, which on average was seventy-six days. One Type IX—Rosenstiel’s U-502—was lost in the Bay of Biscay. The “exchange rate” of these boats was thus ninety-five to one, a kill ratio never again achieved in the war.

Six of the thirteen Type IXs that sailed to the Americas refueled, including the lost U-502. These six patrolled for an average eighty-three days. The seven IXs that did not refuel patrolled for an average of seventy days. Thus refueling added an average of about thirteen days of patrolling for the six boats of this group. These six sank an average of 6.3 ships per boat per patrol. The seven boats that did not refuel sank an average of 8.1 ships per boat patrol.

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