Waterloo

Waterloo was a town in Belgium. Napoléon Bonaparte's French empire was defeated in a battle there and it was a major turning point of the war. Both the Second Doctor and the Sixth Doctor were present at Waterloo. (PROSE: World Game; AUDIO: The Curse of Davros)

The Fourth Doctor told a Sontaran Marshal that it was having its Waterloo when the Doctor managed to block its invasion of a future Earth. (TV: The Sontaran Experiment)