Original sentence: Devonport Dockyard was kept busy for many years
Edited sentence: By the time this work ended in the late 1970s the nuclear submarine base was operational.Devonport Dockyard was kept busy for many years refitting aircraft carriers such as the Ark Royal.However the Royal Citadel has been home to 29th Commando Regiment Royal Artillery since 1962, and 42 Commando Royal Marines has been based at Bickleigh Barracks, a few miles outside Plymouth, since 1971.In May 2003 hundreds of servicemen and women from both Commandos returned to Plymouth after serving in Iraq, to the same homecoming welcomes that must have taken place many times in the city's 300 years as a garrison town.In the 1950s a new Royal Navy Engineering College was built at Manadon, and HMS Raleigh, the current basic training facility of the Royal Navy, was opened west of Torpoint.The army had substantially left the city by 1971, with Raglan Barracks and Plumer Barracks pulled down in the 1960s