Answer: He was exiled to the small island of Elba in the Mediterranean and later, Saint Helena
Explanation: After Napoleon was defeated at the Battle of Waterloo, he was exiled to an island in the Mediterranean. He escaped before being brought back and transferred to a more remote island of Saint Helena to stay there as the coalition who defeated him knew he'd keep fighting til he couldn't anymore, so they removed his ability to raise an army, rule, or make war.
Throughout the rest of his life he tried to keep a sense of royalty and control over the island until eventually he got so bored he started to hate his life.
Side note: Most of the "There's nothing we can do" images of Napoleon come from those days of monotonous boredom and self pity in exile.