Following the acquisition of the Mexican Cession in the Treaty of Guadalupe Hidalgo that ended the Mexican–American War, the small Federal garrison west of the Rocky Mountains was spread out over that vast territory.
Following statehood, the California State Militia engaged in most of the early conflicts with the Indians within its boundaries before the American Civil War.
Minor skirmishes occurred between local militias or volunteers and the Yahi, Yana and Paiute in northeastern California into the 1870s.
Following the Civil War, most hostilities in California were over except for a few minor skirmishes in the Owens Valley and in the Mojave Desert against the Timbisha and Chemehuevi.
Federal troops replaced the volunteers between late 1865 and early 1866 and again engaged in military actions in the remote regions of the Mojave Desert, Owens Valley and the northeast of the state against the Snakes and later the Modoc in the next two decades.