sentences:  Owing to the shared convictions of the democratically elected government of Juárez and U.S. President Lincoln, Matías Romero, Juárez's minister to Washington, mobilized support in the U.S. Congress and the U.S. protested France's violation of the Monroe Doctrine.Once the American Civil War came to a close in April 1865, the U.S. allowed supporters of Juárez to openly purchase weapons and ammunition and issued stronger warnings to Paris.Napoleon III ultimately withdrew his army in disgrace, and Emperor Maximilian, who remained in Mexico even when given the choice of exile, was executed by the Mexican government in 1867.