26 It was early in the war: Zentner tells this story in Thomas’s Raiders, 87–89.
The literature on U-boats is full of stories that can only make you wonder why on earth any young man would ever join Germany’s submarine service. Case in point: One boat, U-18, attempted an attack on Britain’s main fleet based in Scapa Flow, off northern Scotland, but was spotted and rammed by a patrol vessel, a trawler. The collision damaged the boat’s periscope and the horizontal rudders—the hydroplanes—that controlled its ascent and descent. The captain ordered an emergency dive, but the boat plunged to the bottom, then shot back up to the surface, out of control. There it was rammed a second time, now by a destroyer. The U-boat sank but struggled back to the surface, where it drifted, disabled. The captain signaled surrender. The destroyer managed to rescue all but one member of the crew.
On another U-boat, during a practice dive, the commander dashed from the conning tower at the last minute and slammed the hatch behind him. It didn’t close. As the boat went below the surface, water surged in and quickly began flooding the interior. The boat sank 90 feet. The water rose so quickly that for some crew it was soon at neck level. It was then that one crewman, himself nearly submerged, thought to engage the boat’s compressed-air apparatus, which blew water from its diving tanks. The boat shot to the surface. The crew engaged its internal pumps, and the water quickly disappeared. “But suddenly,” recalled Leading Seaman Karl Stoltz, “the whole interior was filled with a greenish choking vapor—chlorine gas from the water that had flooded the electric battery.” The captain ordered all the men out on deck, except for an engine-room mechanic and the helmsman. Fresh air flowing through the hatch thinned the gas.
The cause was a simple error by the captain. The hatch, once closed, was supposed to be sealed in place using a wheel that operated a series of clamps, but before the dive the captain had mistakenly turned the wheel the wrong way, setting the clamps in their sealed position, thus blocking the hatch from closing. Stoltz estimated that the crew had been just seconds away from being drowned.
Even the stealth of U-boats, their main asset, could work against them. On January 21, a U-boat of the same class as Schwieger’s U-20 was on patrol off the coast of Holland when its crew spotted another submarine. Presuming at first that this was another German boat, they tried twice to hail it but got no answer. The U-boat’s captain, Bruno Hoppe, now decided the other submarine must be British and launched an attack. He sank it with one torpedo, then moved close to attempt to rescue survivors. There was only one, who now informed him the boat he had just destroyed was in fact the German navy’s own U-7, under the command of Hoppe’s closest friend. “The two men had been inseparable for years,” according to U-boat captain Baron von Spiegel, who knew them both.
For these and other stories, see Gibson and Prendergast, German Submarine War, 17–18, 20; Neureuther and Bergen, U-Boat Stories, 154–57; Thomas, Raiders, 171–72.
27 Depth charges did not yet exist: Depth charges were first deployed in January 1916 but initially were not very effective. They would not become a significant threat to U-boat commanders for another year. Sonar—the source of the iconic “ping” in submarine movies—would not be introduced until after World War I. Breemer, Defeating the U-Boat, 34; Marder, From the Dreadnought, 350.
28 This was a strenuous maneuver: Forstner, Journal, 14–15.
29 oil-laced water: Neureuther and Bergen, U-Boat Stories, 25.
30 Throughout Friday: Schwieger, War Log.