Tubac was for a spell, the Capital of Sonora. While the USA was preoccupied with the Civil War, the French empire of Napoleon III, wanting to renew the French influence in North America, saw an opportunity to invade Mexico. It lasted from 1861 until they were driven out in 1867, displacing the government of Benito Juarez. Maximilian was made emperor. The French army landed in 1861. Their plan was to take Mexico City, but the Mexican army defeated them at the Battle of Puebla on May 5, 1862, Cinco de Mayo (sound familiar *) delaying their taking the capital city for a year.
On March 29, 1865, a French squadron arrived by sea to the port city of Alamos and then captured Guaymas. Moving north to Hermosillo, Sonora.
Sonora Governor Ignacio Pesqueira, eluding the French, escaped into Arizona and took refuge in Tubac, where he declared the town the “the Capital City of Sonora.” He remained there until the French were driven out. At the same time Benito Juarez took refuge in El Paso Del Norte.
*Mexican Independence Day is often referred to as “El Grito” or “El Grito de Independencia,” a tribute to the battle cry that launched a rebellion in 1810 leading to independence from Spain. Like America’s 4th of July. In America the holiday is often confused with Cinco de Mayo and incorrectly referred to as Mexico’s Independence Day. Perhaps because Cinco de Mayo rolls off the gringo’s tongue much easier than Dieciséis de Septiembre