* U-boats that fired torpedo or used the deck gun

On 1 Dec, 1943, the convoy KN-280 left Key West consisting of five tankers from Galveston and five freighters from Key West and were shortly thereafter joined by Libertad from Miami. The convoy was slowed down by two ships that were unable to keep up the speed until they were ordered to proceed unescorted on the stragglers route to avoid further delay in the morning of 3 December, on this occasion the Libertad was moved from station #34 to #13. The night of 3/4 December was rainy and moonless and USCGC Dione failed to spot U-129 in the darkness when she dropped back on the port quarter of the convoy to investigate a radar contact.

At 07.30 hours on 4 December, U-129 had dived after being warned by her radar detector and picked up the approaching ships of convoy KN-280 on the hydrophone. Surfacing after 30 minutes, the U-boat immediately launched an Aphrodite radar decoy balloon and headed directly for the convoy, being passed on an opposite course in a distance of about 1000 meters by USCGC Dione which had dropped back on the port quarter of the convoy to investigate the radar contact caused by the decoy. It was a rainy and moonless night and the look-outs aboard the escort did not realize that they just have passed a U-boat and even tried to exchange recognition signals. U-129 undeterred continued to approach the now undefended side of the convoy and fired a full salvo of four torpedoes at the Libertad in station #13, the last ship of the outmost column on the port side. The ship sank almost immediately after being hit by two torpedoes, so quickly that none of the other ships in the convoy noticed the attack. Only two muffled explosions were heard and some lights seen astern, but assumed that this came from depth charges dropped by USCGC Dione and USCGC Argo was sent to investigate and conduct a search, but found nothing. Furthermore the convoy commodore and escorts were distracted as shortly after the attack the convoy had to evade the oncoming convoy NK-581 with a turn to starboard and only at daybreak it was noticed that one of the ships was missing. The U-boat managed to leave the area on the surface without being discovered by any of the escorts.

Only at daybreak it was noticed that Libertad was missing and several patrol vessels and aircraft were sent to search for her. The convoy KN-280 consisted only of eight ships when it had to evade an oncoming group of landing craft that went unnecessarily close to the convoy in the evening and only a few hours later the Norfolk section of convoy GUS-21 had to be evaded in fog with two or more ships cutting diagonally through the convoy from ahead. The US freighter Courageous in station #32 carried out an ordered turn to port, but the first two ships of the second column had not observed the signal and she just passed astern the first ship but was struck on the port quarter by the US tanker Pan-Georgia in station #22. No serious damage was suffered by either vessel. The Courageous proceeded independently and entered New York City ahead of the convoy, while the other vessel rejoined the convoy and reached port on 6 December.