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.
Yuma Expedition
Following the failure of the California Militia against the Quechan people ("Yuma Indians"), in the Gila Expedition, the U. S. Army sent the Yuma Expedition under Captain Samuel P. Heintzelman, to establish a post at Yuma Crossing of the Colorado River in the vicinity where it met the Gila River in the Lower Colorado River Valley region of California. He was to protect travelers on the overland route from the east to California and to quell any hostilities by the Quechan people ("Yuma Indians").