The sixth season of British science fiction television series Doctor Who began on 10 August 1968 with the first story of season 6 The Dominators and ended Patrick Troughton's reign as the Doctor with its final story The War Games. Only 37 out of 44 episodes are held in the BBC archives; 7 remain missing. As a result, 2 serials are incomplete: only episode 2 of the 6-part story The Space Pirates still exists, while The Invasion has had its two missing episodes (episodes 1 and 4) reconstructed using animation.