Born in Berlin on the 26th of November, 1908, Gerhard Bigalk entered into the German Kriegsmarine in 1934. In October 1935 he began reconnaissance training in the naval air force, and in 1937 made 21 combat flights in the Spanish Civil War, which won him the Spanish Cross (1 Jun 1939).

He spent time a little time on merchant ships before transferring to the submarine service in November 1939, and serving as commander aboard the training boat, U-14 (a type IIB U-boat). He also received the rank of Kapitänleutnant, which he held until after his death in 1942.

On January 31, 1941, Bigalk took command of the newly comissioned U 751, a type VIIC U-boat in the Atlantic theatre. In December of that year, his boat participated in an attack on the HG 76 convoy, which was heavily escorted. U-131 and U-434 were both sunk with all hands during this attack. The British aircraft carrier Audacity shot down 2 Luftwaffen FW-200 Long-range patrol aircrafts. In response, U-751 got closer to the carrier in the twilight hours and torpedoed it, sending the 11,000-ton carrier to the sea bottom with crew and aircraft. For the sucess of his crew, Bigalk received the Iron Cross 1st Class, and the Knights Cross of the Iron Cross on the 26th of December from the Führer.

His boat went on to sink 2 ships and damaging another in February 1942. In a patrol in May, Bigalk managed to down two more ships bringing his record to 6 ships totalling 32,412 tons.

Bigalk's U-751 was on its 7th war patrol in Cape Ortegal, when it came under attack by Allied aircraft on the 17th July, 1942. U-751 sunk with all hands on board.

Gerhard Bigalk was awarded the rank of Korvettenkapitän, after his death, in May 1945 as an honor.