Yuma War
The Yuma War was the name given to a series of United States military operations conducted in southern California and what is today southwestern Arizona from 1850 to 1853. The Yumans were the primary opponent of the United States Army, though engagements were fought between the Americans and other native groups in the region. Conflict generally took the form of guerrilla warfare, and, over the course of three years, the army engaged in pursuing unfriendly natives, protecting American settlers crossing the Colorado River and preventing conflict between the native tribes. A peace treaty in summer of 1853 was signed, ending hostilities between the Yuma and the United States, but it sparked a short war between the Yuma and the Cocopah. During the conflict, the historic Fort Yuma was constructed and became an important outpost on the frontier.
Imperial Valley
Fort Yuma is located on the banks of the Colorado River in Winterhaven, California. First established after the end of the Mexican–American War in 1848, it was originally located in the bottoms near the Colorado River, less than below the mouth of the Gila River. It was to defend the newly settled community of Yuma, Arizona on the other side of the Colorado River and the nearby Mexican border. In March 1851 the post was moved to a small elevation on the Colorado's west bank, opposite the present city of Yuma, Arizona, on the site of the former Mission Puerto de Purísima Concepción. This site had been occupied by Camp Calhoun, named for John C. Calhoun, established in 1849. Fort Yuma was established to protect the southern emigrant travel route to California and to attempt control of the warlike Yuma Indians in the surrounding area.