Fort Fillmore was a United States military fortification established by Colonel Edwin Vose Sumner in September 1851 near Mesilla in what is now New Mexico, primarily for the purpose of protecting settlers and traders traveling to California. Early frontier migrants were under constant threat from attack by local Native Americans, and a network of forts was eventually created by the U.S. government to protect and encourage westward expansion. Fort Fillmore was intended to protect a corridor plagued by hostile Apaches, where several migration routes converged between El Paso and Tucson to take advantage of Apache Pass.