linguistic:voice_change, information:extraction
Forts and outposts

As the frontier moved westward, the establishment of U.S. military forts moved with it, representing and maintaining federal sovereignty over new territories. The military garrisons usually lacked defensible walls but were seldom attacked. They served as bases for troops at or near strategic areas, particularly for counteracting the Native presence. For example, Fort Bowie protected Apache Pass in southern Arizona along the mail route between Tucson and El Paso and was used to launch attacks against Cochise and Geronimo. Fort Laramie and Fort Kearny helped protect immigrants crossing the Great Plains and a series of posts in California protected miners. Forts were constructed to launch attacks against the Sioux. As Indian reservations sprang up, the military set up forts to protect them. Forts also guarded the Union Pacific and other rail lines. Other important forts were Fort Sill, Oklahoma, Fort Smith, Arkansas, Fort Snelling, Minnesota, Fort Union, New Mexico, Fort Worth, Texas, and Fort Walla Walla in Washington. Fort Omaha, Nebraska, was home to the Department of the Platte, and was responsible for outfitting most Western posts for more than 20 years after its founding in the late 1870s. Fort Huachuca in Arizona was also originally a frontier post and is still in use by the United States Army.