Battle of Waterloo

The Battle of Waterloo took place on 18 June 1815 in the Belgian province of Waterloo. (BFA: The Curse of Davros) It saw the defeat of the reconstituted French imperial army of Napoléon Bonaparte by the British under the Duke of Wellington and the Prussians under Marshal Blucher. The time-manipulating Players tried to subvert this by assassinating the Duke before the battle and then issuing false orders to the Prussian reinforcements. These attempts were thwarted by the Second Doctor and his companion Serena. Serena sacrificed herself to take the shot that would have killed the Duke. The Doctor later posed as Napoleon to pass safely through French territory and deliver the message to the Prussians. This defeat marked the end of the French empire. Bonaparte was deposed as Emperor for the second time and once again exiled. (PDA: World Game)

As part of a plan to conquer Earth, Davros attempted to alter the outcome of the Battle of Waterloo by providing Napoleon with Dalek weapons, but when Napoleon learned of Davros's true agenda from the Sixth Doctor, he deliberately allowed himself to lose to save humanity from being conquered by the Daleks (BFA: The Curse of Davros).

After the battle, Wellington told the Doctor, "The only thing sadder than a battle lost, is a battle won." Some time later, the Fourth Doctor considered how right he was. (EDA: The Eight Doctors)

Wellington fought alongside Oliver Blazington at the battle. (NSA: The Eye of the Jungle)

'Waterloo' has become a byword for defeats. For example, the Fourth Doctor referred to the defeat of the Sontarans as "their Waterloo". (DW: The Sontaran Experiment)

While teaching at Farringham School for Boys in November 1913, John Smith gave a lesson on Napoleon's defeat at Waterloo. (DW: Human Nature)

In a history project for school, Clyde Langer and Luke Smith were required to show the battle strategies by Wellington and Napoleon at the battle. The pair re-enacted the battle on Mr Smith. (SJA: The Last Sontaran)

Alternative timeline
In an alternative timeline where the Players assassinated the Duke of Wellington before the Battle, the French forces won. The Countess convinced Napoleon to continue his plans for the expansion of France regardless of the strain that he put on his men. As a result, the empire he created had collapsed by 1865. The countries he had conquered reverted to smaller kingdoms. They engaged in minor conflicts with each other. This timeline was negated when the Second Doctor learned how the Duke had died. He travelled back to the night of his assassination to avert it. (PDA: World Game)