U-505 was a near absolute failure as a killer, failing to sink a single ship for multiple combat tours in a row, suffering the only suicide of a commanding officer in the German undersea service until the final days of the war, and becoming the first U-boat captured in the war despite failed attempts to scuttle the ship. Yeah, the crew couldn't even sink the sub properly.
The boat, U-505, would earn the moniker "unluckiest" for its struggles, though some of its former crew members have pushed back against that, saying that the boat should not be blamed since it got nearly all of its crew home every tour despite its struggles.
Kapitänleutnant Axel-Olaf Loewe commissioned the boat in August 1941 and led it on three tours, sinking seven ships. (Kapitänleutnant is roughly equal to a U.S. Navy lieutenant, the O-3 grade.) Loewe did have one black spot on his record, though.
On July 22, 1942, a misunderstood command led to the ship shooting off the mast of a sailing boat with no flag and then sinking it. The ship belonged to a Columbian diplomat, and Columbia declared war after the incident. Berlin wasn't exactly worried about Columbia, but that still ended up being Loewe's last patrol.
Loewe then relinquished command to Kapitänleutnant Peter Zschech who had a much rougher time on the boat.
Zschech had been a successful officer before his command, and he held two Iron Crosses when he arrived on the U-505. He was expected to be a star. But his first two patrols had resulted in only one sinking. Before he could leave for his third patrol, French dockworkers sabotaged the U-505. They were executed, but their sabotage had the desired effect.
The U-505 struggled on its sixth patrol and sank no ships. Its seventh, eighth, and ninth patrols were cut short as the crew kept hearing strange noises that likely represented ongoing problems from the sabotage, and the boat turned back from each tour.
Zschech was professionally embarrassed. He was supposed to be a star of the submarine service but had sank one ship over the course of six patrols. On Oct. 9, 1943, Zschech took the crew on its 10th overall patrol, his seventh. Fifteen days later, the U-505 was spotted and came under heavy, determined depth charge attack.
Zschech pulled his pistol and took his own life. It was the only suicide of a submarine commanding officer during a war patrol for all of World War II. (Three other U-boat commanding officers would take their lives on shore during or after the war, but Zschech was the only to do so during a combat patrol.)
The Oberleutnant zur See Paul Meyer got his crew out of the depth charge attack and led them back to port. The ship received a new commanding officer, Oberleutnant zur See Harald Lange. His first patrol on the boat lasted only nine days with little effect. But his next patrol, launched March 16, 1944, would go for 81 days. But it would end horribly.
It wasn't entirely Lange's or the crew's fault. The U.S. Navy Task Group 22.3 had successfully sunk U-515 on its previous tour, and the task group commander had gotten an idea for a greater coup. U-515 had, after suffering extreme damage, come to the surface in the middle of the task group. The task group quickly sank it with all the guns it had, but the commander wanted to try using only machine guns next time, hoping to save the sub and capture it.
Unluckily for the U-505, it was the next sub that Task Group 22.3 got its teeth into. The group had found no radar contacts on its May 1944 patrol and was headed back to refuel on June 2 when the group got a radar hit 50 miles east. That was followed by a June 4 sound contact in the area.
The USS Chatelain was the first to attack after Wildcat fighters from the USS Guadalcanal spotted the U-505, and it's depth charges quickly forced the sub to surface. U-505 began circling to the right, and the gunners of the task group began laying into it out of fear it was lining up for a torpedo attack. This quickly proved false as submariners started leaping into the ocean, and the group commander ordered the larger caliber weapons to cease fire.
He broadcasted, "I want to capture that bastard, if possible." He allowed the anti-aircraft gunners and machine gunners to fire a little longer, then ordered his boarding parties to attack the sub.
It was the first capture of an enemy ship by a U.S. Navy vessel since 1815. The boarding parties quickly got classified materials and the enigma machine out, and then set about trying to save the boat. This required closing the scuttling vents, disabling the charges, and then pumping water out of the boat.
And the U-505, in either a final slap in the face of its German crew or a final act of supporting sailors, depending on who you ask, the boat's pumps successfully cleared the water, and it was towed to the Caribbean for study. The surviving crew members sat out the rest of the war in a POW camp.