The first U.S. Army post established in Montana was Camp Cooke on the Missouri River in 1866 to protect steamboat traffic going to Fort Benton, Montana. More than a dozen additional military outposts were established in the state. Pressure over land ownership and control increased due to discoveries of gold in various parts of Montana and surrounding states. Major battles occurred in Montana during Red Cloud's War, the Great Sioux War of 1876, the Nez Perce War and in conflicts with Piegan Blackfeet. The most notable of these were the Marias Massacre (1870), Battle of the Little Bighorn (1876), Battle of the Big Hole (1877) and Battle of Bear Paw (1877). The last recorded conflict in Montana between the U.S. Army and Native Americans occurred in 1887 during the Battle of Crow Agency in the Big Horn country. Indian survivors who had signed treaties were generally required to move onto reservations.

What was the name of the first US Army post?