Last Battle of the Seventh Galaxy

The Last Battle of the Seventh Galaxy was the name given by historians to an event in an intergalactic war. The Tenth Doctor described it as an unprovoked and avoidable massacre. All of the weapon's creators died, but the Tenth Doctor believed that their sacrifice made no difference because their enemy survived.

As a result of the weapon used during the battle, countless star systems were annihilated. Two hundred million people perished on Arcopolis alone, but they weren't even noticed by the historians because they made up such a small fraction of the overall casualty figure. (PROSE: The Eyeless)