The Crabb massacre was the culmination of the eight day Battle of Caborca. It was fought between Mexico and their O'odham allies against American forces in April 1857. Due to the outbreak of the Reform War in Mexico, the rebel Ygnacio Pesqueira invited the American politician Henry A. Crabb to colonize the northern frontier region in the state of Sonora, on the basis that the colonists would help Pesqueira fight in the civil war and against the Apache.