History of Europe

What or who kept the US from challenging French control of Mexico?

The United States did challenge French control of Mexico, leading to the French–Mexican War (1861–1867). The US supported the Mexican republican government of Benito Juárez against the French-imposed Second Mexican Empire of Maximilian I. The United States provided financial and military aid to the Mexican government, and even threatened to declare war on France if they did not withdraw their troops. Ultimately, the French withdrew their troops in 1867, and Maximilian I was executed by the Mexican government.