7 Jan 1944
Aircraft attack, aircraft shot down: British Wellington HF245 (RAF Sqdn 36/Y, pilot F/O R.D. Bamford, RNZAF)

U-343 was attacked at 20.30 hrs, two days after passing the Straits of Gibraltar into the Mediterranean. The Wellington made a low level attack, dropping five depth charges which fell astern and missed, and was hit by flak in the port wing and caught fire. It was forced to ditch shortly afterwards, and the pilot and navigator were killed. The remaining four aircrew were rescued from their dinghy by ORP Slazak the next morning.

The sighting report from this aircraft led another Wellington (HF221, RAF Sqdn 36/M, pilot F/O J.T. Hutton) to the scene, which immediately attacked U-343. Its depth charges fell wide because the port engine was hit by flak and the aircraft became difficult to control, despite which it managed to return to Bone (now Annaba), Algeria and land safely.

8 Jan 1944
Aircraft attack, aircraft shot down: British Wellington (RAF Sqdn 179/R, pilot F/O W.F.M. Davidson)

Following two aircraft attacks on the boat the previous day, the Allies initiated a Swamp operation, and at 21.40 hrs Wellington "B for Baker" of 36 Sqdn RAF located U-343 SW of Cartagena. She was then attacked by a Wellington from 179 Sqdn piloted by W/C J.H. Greswell DFC, followed by a second aircraft from 179 Sqdn. Wellington R-Robert dropped six depth charges, but several AA hits set the port wing on fire and the aircraft crashed into the sea, killing five of the crew. Only the pilot survived, after being thrown clear. U-343 passed close to his dinghy twice, but the Germans did not take him prisoner because they had "more important things to do". He was picked up by HMS Active the next morning and later received the DFC.

The boat had already sustained damage in these attacks, but there was more to come, as a Catalina (202 Sqdn RAF, pilot F/L J. Finch) then continued the attack. The aircraft broke off the attack at 23.00 hrs, and only then because flak had damaged the port wing, fuselage and both fuel tanks and wounded the flight engineer. U-343, badly damaged and unable to dive, managed to escape in the darkness, with only one man wounded by strafing, and following repairs at sea managed to reach her new base at Toulon.

2 recorded attacks on this boat.