"U-156" was soon crammed above and below decks with nearly 200 survivors, including five women, and had another 200 in tow aboard four lifeboats. At 6 a.m. on 13 September, Hartenstein broadcast a message on the band in English—not in code—to all shipping in the area, giving his position, requesting assistance with the rescue effort, and promising not to attack. It read: "If any ship will assist the shipwrecked Laconia crew I will not attack her, providing I am not being attacked by ship or air force. I picked up 193 men. 4°-53" South, 11°-26" West. – German submarine." The British in Freetown intercepted this message but, believing it might be a ruse of war, refused to credit it. Two days later, on 15 September, a message was passed to the Americans that "Laconia" had been torpedoed and the British merchant ship was en route to pick up survivors. The "poorly composed message" implied that "Laconia" had only been sunk that day and made no mention that the Germans were involved in a rescue attempt under a cease-fire or that neutral French ships were also en route. "U-156" remained on the surface at the scene for the next two and a half days. At 11:30 a.m. on 15 September, she was joined by "U-506", and a few hours later by both and the . The four submarines, with lifeboats in tow and hundreds of survivors standing on their decks, headed for the African coastline and a rendezvous with the Vichy French surface warships that had set out from Senegal and Dahomey. During the night the submarines became separated. On 16 September at 11:25 a.m., "U-156" was spotted by an American B-24 Liberator bomber flying from a secret airbase on 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." 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."