Ender destroys bugger homeworld (Third Invasion)

Ender, believing he is playing a simulation, commands the human fleet in a battle against the Buggers. The enemy is overwhelmingly numerous, and Ender decides to attack the planet itself, using the Little Doctor. The planet explodes, and the entire Bugger fleet is destroyed. Ender later learns that the battle was real, and he has committed genocide, wiping out an entire alien species. He is devastated and feels immense guilt. The victory is celebrated by humanity, but Ender is traumatized.