Editing Laconia incident (section)

=== First American attack ===
During the night the submarines became separated. On 16&nbsp;September at 11:25&nbsp;a.m., ''U-156'' was spotted by an American [[Consolidated B-24 Liberator|B-24&nbsp;Liberator]] bomber flying from a secret airbase on [[Ascension Island|Ascension]]. The submarine was travelling with a Red Cross flag draped across her gun deck. Hartenstein signalled to the pilot in both [[Morse code]] and English requesting assistance. A British officer also messaged the aircraft: "RAF officer speaking from German submarine, ''Laconia'' survivors on board, soldiers, civilians, women, children."{{sfn|Hood|2006|p=335}}

Lieutenant James D. Harden of the [[US Army Air Forces]] did not respond to the messages; turning away, he notified his base of the situation. The senior officer on duty that day, Captain [[Robert C. Richardson III]], who claimed that he did not know that this was a Red Cross-sanctioned German rescue operation, ordered the B-24 to "sink the sub". Richardson later claimed he believed that the rules of war at the time did not permit a combat ship to fly Red Cross flags. He feared that the German submarine would attack the two Allied freighters diverted by the British to the site. He assumed that the German submarine was rescuing only the Italian POWs. In his tactical assessment, he believed that the submarine might discover and shell the secret Ascension airfield and fuel tanks, thus cutting off a critical Allied resupply air route to British forces in Egypt and Soviet forces in Russia.{{sfn|Maurer|Paszek|1964|pp=338–344}}

Harden flew back to the scene of the rescue effort and, at 12:32&nbsp;p.m., attacked with bombs and depth charges. One landed among the lifeboats in tow behind ''U-156'', killing dozens of survivors, while others straddled the submarine itself, causing minor damage. Hartenstein cast adrift those lifeboats still afloat and ordered the survivors on his deck into the water. The submarine submerged slowly to give those still on the deck a chance to get into the water and escape. According to Harden's report, he made four runs at the submarine. On the first three the depth charges and bombs failed to release, on the fourth he dropped two bombs. The crew of the Liberator were later awarded medals for the alleged sinking of ''U-156'', when they had in fact only sunk two lifeboats.{{sfn|Blair|1998|p=63}}

Ignoring Hartenstein's request that they stay in the area to be rescued by the Vichy French, two lifeboats decided to head for Africa. One, which began the journey with 68&nbsp;people on board, reached the African coast 27&nbsp;days later with only 16&nbsp;survivors. The other was rescued by a British trawler after 40&nbsp;days at sea. Only four of its 52&nbsp;occupants were still alive.<ref name=":0" />

Unaware of the attack, ''U-507'', ''U-506'', and ''Cappellini'' continued to pick up survivors. The following morning Commander Revedin of ''Cappellini'' found that he was rescuing survivors who had been set adrift by ''U-156.'' At 11:30&nbsp;a.m. Revedin received the following message: "Bordeaux to Cappellini: Reporting attack already undergone by other submarines. Be ready to submerge for action against the enemy. Put shipwrecked on rafts except women, children, and Italians, and make for minor grid-square&nbsp;56 of grid-square&nbsp;0971 where you will land remainder shipwrecked on to French ships. Keep British prisoners. Keep strictest watch enemy planes and submarines. End of message."{{sfn|Bridgland|2001|p=79}}

''U-507'' and ''U-506'' received confirmation from headquarters of the attack on ''U-156'' and were asked for the number of survivors rescued. Commander Schacht of ''U-507'' replied that he had&nbsp;491, of whom 15&nbsp;were women and&nbsp;16 were children. Commander Wurdemann of ''U-506'' confirmed&nbsp;151, including nine women and children. The next message from headquarters ordered them to cast adrift all the British and Polish survivors, mark their positions and instruct them to remain exactly where they were, then proceed with all haste to the rescue rendezvous. The respective commanders chose not to cast any survivors adrift.<ref>{{Cite news |last=Tougias |first=Michael J. |title=So Close to Home: U-boats in the Gulf of Mexico |pages=30 |work=Sea History: The Art, Literature, Adventure, Lore & Learning of the Sea |issue=155 |publication-date=Summer 2016 |url=https://issuu.com/seahistory/docs/sh_155_summer-2016/32 |access-date=September 25, 2023}}</ref>

The order given by Richardson and the resulting attack by Harden have been called {{lang|la|[[prima facie]]}} [[Allied war crimes]]. Under the conventions of war at sea, ships—including submarines—engaged in rescue operations are held to be immune from attack.{{sfn|Mallison|Mallison|1993|p=94}}