For 63 years Chatham Dockyard undertook refits of conventional (non-nuclear) submarines for the Royal Navy. The first submarine to be refitted at Chatham Dockyard was HMS A1 in 1911. During the 1950s, Chatham Dockyard's workforce gained valuable experience in the converting and modernising of both 'T' and 'A' class submarines. In November 1969, Alliance and Aeneas became the last 'A' class submarines to be refitted here. As Alliance re-commissioned in May 1970, the Dockyard's Admiral Superintendent, Rear Admiral Frederick Lawson, sent her the following message:
"I submit that no ship in my experience has been in a better state of completion or cleanliness at the end of a refit than
Alliance is today. This has fittingly marked the climax and conclusion of a long series of 'A' class refits conducted at Chatham Dockyard in happy collaboration with officers and men of the Submarine Service."
Conventional submarine refitting was discontinued in the mid 1970s to allow Chatham's workforce to concentrate on nuclear fleet submarine refitting work.
