1 Apr 1942
U-77 was attacked by a Swordfish aircraft in the Mediterranean, leaving the boat badly damaged and unable to dive.

4 Jul 1942
HMS Thrasher (Lt. H.S. Mackenzie, DSO, RN) fired three torpedoes at U-77 in position 32º48N, 33º36E. All torpedoes missed. Thrasher then surfaced to engage with gunfire, but U-77 dived and escaped.

13 Nov 1942
The depth charge attack on 13 Nov 1942 by British corvettes HMS Lotus and HMS Poppy, credited with sinking U-605 was in fact against U-77, which escaped with only minor damage (Sources: 1987-07-01, FDS/NHB)

28 Mar 1943
The sinking of U-77 The boat was sighted at 11.25 hrs by a Hudson Mk.VI (48 Sqn RAF/L, pilot F/O J.B. Harrop) on patrol east of Cartagena in position 37°42N/00°10E, and dived immediately on being attacked. The aircraft dropped depth charges just ahead of the diving point. Oil and air bubbles were observed on the surface as water entered through a serious leak in the engine room, which forced U-77 to surface later, unable to dive. Hartmann reported his situation to the FdU while en route to Toulon, and was instructed to enter the neutral port of Alicante to make repairs under international maritime law. U-380 (Röther) was ordered to meet the boat to take off most of the crew to avoid internment in Spain, but before that could happen, Hudson Mk. IIIA T9430 (RAF Sqdn. 233/L, pilot F/O E.F. Castell) found U-77 at 17.45 hours between Cabo San Antonio and Ibiza. Despite fierce flak, the aircraft made several attack runs, firing 3000 rounds of .303 ammunition and dropping four depth charges and a single A/S bomb, which detonated only 15 yards abaft the stern, for which F/O Castell was awarded the DFC. The badly damaged boat managed to escape with the coming of dusk and continued to Alicante, but during the night both electric motors broke down and as she lost way U-77 began to go down, sinking at 01.15 hrs on 29 March south of Cape Nao, Spain (the wreck has been located at a depth of 80 metres in position 38°33.334N/00°14.875E.) The crew abandoned ship in one rubber dinghy and makeshift rafts made from deck planks, but the commander and 37 others died from exposure or drowning. Several hours later, nine survivors were rescued by a Spanish fishing boat from Denia. They landed at Altea on 30 March, and were eventually repatriated. 36 bodies washed ashore in Spain, the commander and four men being buried at Altea, and 31 others at Calpe. In 1983 they were reinterred at the cemetery at Cuacos de Yuste, Provincia de Cáceres, Spain.

4 recorded attacks on this boat.