Napoleon III attempted to gain British support when he invaded Mexico and forcibly put his pawn Maximilian I on the throne. London was unwilling to support any action other than the collection of debts owed by the Mexicans. This forced the French to act alone in the French Intervention in Mexico. Washington, after winning the civil war, threatened an invasion to expel the French and Napoleon pulled out its troops. Emperor Maximilian remained behind and was executed. When Napoleon III was overthrown in 1870, he fled to exile in England.