THURSDAY MORNING, MAY 6, FOUND U-20 ADVANCING slowly along the southwest coast of Ireland, into waters mariners knew as the St. George’s Channel. Though the term channel connotes a narrow body of water, the St. George’s at its broadest was about 90 miles wide, tapering to 45 miles between Carnsore Point on the Irish coast and St. David’s Head in Wales. A lightship was anchored at the Irish side to steer ships away from a notorious hazard, the Coningbeg Rock, routinely misspelled by telegraph and wireless operators as Coningberg or Koninbeg. Beyond this point, the waters broadened again to form the Irish Sea, Muir Éireann, with Liverpool another 250 nautical miles to the north and east. Even at Schwieger’s best speed of 15 knots, he would need another sixteen hours to reach his assigned patrol zone.
But the weather was not cooperating. Persistent fog had forced him to remain submerged throughout the night. Just before 8:00 A.M., he found signs of clearing and brought the boat to the surface, but did so using only its hydroplanes. He kept the diving tanks filled with seawater in case of emergency. The boat moved through striations of heavy fog.
A steamship appeared ahead, off to starboard. It flew no flag and showed no other indicator of registry. Schwieger ordered his gun crew on deck for a surface attack. Despite the poor visibility, some sharp-eyed soul aboard the steamer spotted the submarine. The ship turned hard and fled at full speed.
Schwieger raced after it, his gun crew firing round after round. Two shells hit the steamer, but it continued to run. The ship entered a fog bank and disappeared from view. Schwieger followed.
Clarity returned. Schwieger’s men resumed fire. U-20 was making 15 knots; the steamer probably only 8 to 10. The attack went on for nearly two hours, with U-20 gradually gaining, until one shell struck the target’s bridge. This proved persuasive. The steamship stopped and lowered its boats. One foundered, Schwieger saw, but three others pulled away, “full to capacity.”
Schwieger brought the submarine closer. He fired a bronze torpedo into the hull, from a distance of 500 meters (550 yards). It exploded at a point opposite what Schwieger believed to be the ship’s engine room. “Effect slight,” he wrote. The ship sagged at the stern but did not sink.
Schwieger’s gun crew began firing at the ship’s waterline as he brought U-20 slowly around to its stern. The ship’s name had been painted over, but up close Schwieger was able to read it: Candidate. His ship-identification book showed it to be a British freighter of about 5,000 tons, owned by the Harrison Line of Liverpool, a company prone to giving ships such romantic names as Auditor, Administrator, and Electrician.
Schwieger’s men continued firing until the ship’s bow rose high out of the water and the stern began to sink. He recorded the latitude and longitude of the wreck, which put it 20 miles south of the Coningbeg lightship, at about the middle of the narrowest portion of the Saint George’s Channel. The time was 10:30 A.M.
Ten minutes later, he sighted another potential target coming over the horizon, this one the biggest yet, on a course that would converge with his. Fog obscured the ship. Schwieger ordered full speed and set a course that he anticipated would put U-20 ahead of the ship and in position to fire a torpedo.
The big steamer burst from the fog, moving fast. Schwieger saw now that it was a passenger liner of about 14,000 tons. A true prize. He ordered a fast dive and raced at the highest speed his battery-powered engines could muster, 9 knots, but this proved not nearly enough. The ship was still 2 miles off and moving at full speed. Schwieger realized that the best he could do would be to position U-20 so that a torpedo would strike the liner at a glancing 20-degree angle—too oblique to be successful. He called off the attack.
Although he didn’t name the ship in his log, the liner was the Arabic, of the White Star Line, which had owned the Titanic.
AN HOUR LATER, shortly before one o’clock, Schwieger spotted yet another target, ahead and to port.
He set up his attack. This time he chose one of the newer G6 torpedoes and ordered its depth set at 3 meters, about 10 feet. He fired from a distance of 300 meters. The torpedo struck the ship at a point below its forward mast. The bow took on water, but the ship stayed afloat. Its crew fled in boats. Schwieger surfaced.
He determined that the vessel was an English freighter, the Centurion, about 6,000 tons, owned by the same line that owned the freighter he had sunk earlier in the day.
The fog again began to build. Schwieger did not want to take a chance that the Centurion would survive. He fired a second torpedo, “to make foundering sure.” This too exploded on contact, and Schwieger heard the telltale hiss of air that fled the ship as water filled its hull. U-boat commanders always found this a satisfying moment. Kapitänleutnant Forstner, in his memoir, described how the air “escapes with a shrill whistle from every possible aperture, and the sound resembles the shriek of a steam siren. This is a wonderful spectacle to behold!” Often at this point stricken ships gave one last exhalation as water filled their boiler rooms, causing a final explosion and releasing a cloud of black smoke and soot, known to U-boat commanders as “the black soul.”
Schwieger did not wait to see the ship disappear below the surface. The fog had grown too thick. At 2:15 p.m., he submerged and set a course that would take U-20 well out to sea so that he could recharge its batteries in safety and consider how next to proceed.
Schwieger faced a decision. His fuel was running low—surprisingly so—and he had yet to reach his assigned hunting zone off Liverpool, still nearly a day’s voyage away.