Starting in 1862, a growing French army operated in Mexico in an attempt to convert it to a French colonial dependency. The United States wanted them out, but while the American Civil War raged, the US government could do nothing about it but issue threatening statements. In 1865, as one Confederate army after another surrendered, the US Army gathered troops in Texas to threaten a real invasion and underscore American seriousness about the Monroe Doctrine, and the threat proved sufficient - the French pulled out of Mexico, the democratically elected Mexican government was restored to power, and war was averted.

As wargamers we have no moral pressure to avert unnecessary wars such as a U.S. invasion of Mexico in 1866 to forcibly remove Napoleon III's army, so this site exists to help organize and coordinate a wargame campaign for this war that never happened.