Frank Pegler was born in Portsmouth, Hampshire, on 22 February 1906, the son of Henry and Kate Pegler. He joined the Royal Navy as an Engine Room Artificer Apprentice on 6 August 1921. After completing his apprenticeship, he served in the battleships HMS QUEEN ELIZABETH and HMS VALIANT and the cruiser HMS CURACAO. He was next drafted to the destroyer HMS SKATE on 27 October 1928.

Frank Pegler joined submarines when he was drafted to HMS DOLPHIN ‘for the Submarine Course‘ and, on 12 May 1929 he joined HMS H34. This was followed by drafts to HMS L6, HMS OLYMPUS, HMS L21, HMS L26, HMS SEAWOLF, HMS OTWAY, and HMS H31 on 6 March 1937. Frank Pegler was promoted to Warrant Engineer on 1 July 1937.

Frank Pegler was appointed to HMS PHOENIX as the Engineer Officer on 4 October 1938. PHOENIX conducted three war patrols in the Pacific between September and November 1939 and then PHOENIX transferred to the Mediterranean where she arrived on 3 May 1940. A first war patrol in the Mediterranean was conducted off the Island of Crete in June 1940.

A second Mediterranean war patrol started on 3 July 1940 with orders to patrol off the East Coast of Sicily. On 16 July 1940, HMS PHOENIX was lost with all hands and was probably sunk in a depth charge attack by an Italian warship, but it is possible that she accidentally ran into a minefield.

Frank Pegler was the husband of Mary Louise Pegler, and is commemorated on the Portsmouth Naval Memorial on Panel No. 37 Column No. 2.