The successes of the Mexican Empire force…

The successes of the Mexican Empire force Juarez to abandon Chihuahua for the border city of El Paso del Norte (now Ciudad Juarez) in 1865.

Although the conquest of the Republic is nearly complete, the cession of Civil War hostilities in the United States has caused Napoleon III to reexamine the merits of the costly adventure.

Mexican liberals had appealed for military assistance from the United States on the basis of the French violation of the 1823 Monroe Doctrine, but the United States had been involved in its own civil war.

The end of that conflict in the United States in 1865, however, prompts a more assertive foreign policy toward Mexico and releases manpower and arms that are directed to help Juárez in his fight against the French.