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 Quechan (also known as Yuma) were the primary opponent of the United States Army, though engagements were fought between the Americans and other native groups in the region.

After the Mexican Cession, American settlers headed west over the Colorado River to take part in the California gold rush, many of whom crossed over Quechan lands.

This act sparked the beginning of the Yuma War as news of the retaliation spread to California, provoking US military action.

California responded with the Gila Expedition, raising a militia of 142 men who were paid $6 a day to fight the Yuma as opposed to panning gold.

Setting off on April 16, the Gila Expedition entered what is today Arizona only to be besieged and defeated in September after a series of skirmishes.

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).

In October 1851, a letter arrived at San Diego from Lieutenant Sweeny which asked that Heintzelman immediately send aid to the fort.

But when news arrived that four of Sweeny's command had been killed by around 800 Quechan, Cocopah, & Mohave, Heintzelman sent sixteen men under Captain Delozier Davidson with a train of mules and wagons.

The two tribes agreed to join the revolt along with the Cocopah and Quechan in the Yuma War, although the Kumeyaay made no military commitments to attack San Diego.

Heintzelman learned of a December 1851 Cahuilla and Cupeño raid on Warner's Ranch and Agua Caliente in the San Felipe Mountains.

California's American population were very panicked at the possibility of warfare being waged so close to their settlements on the coast, in San Diego concerned citizens began preparing to defend the town in case the Cahuilla and Cupeno attacked there.

Subsequently, the four, named Juan Baustista, Francisco Mecate, Quisil and Luis, were executed by firing squad and buried on December 25, 1851.

Garra was captured at Razon's rancheria in the Coachella Valley, by the Mountain Cahuilla leader Juan Antonio and turned over to the volunteer company from Los Angeles.

American civilians passing by the fort informed the captain that a large party of Quechan were together about forty miles north.

Thirty men were sent to investigate but they returned to Fort Yuma after traveling seventy miles north without encountering the enemy.

Lieutenant Henry B. Hendershott led a third party into Quechan territory around the fort, two villages were destroyed along with several wheat fields and two warriors were killed.

The Quechas, were now threatening the train so immediately upon receiving the message, Heintzelman dispatched fourteen men under Lieutenant Sweeny for protection.

Almost as soon as Sweeny crossed the Colorado, he sent a message back stating that he expected to be attacked by some 800 warriors and that one of Armijo's sheep herders had been killed.

When the captain concluded that he was going the wrong way, he sent a squad back down the Gila but before they had gone a mile, they encountered 100 to 150 mounted Quechan and Cocopah warriors.

The Cocopah also formed an alliance with the Paipai and Halyikwamai and together they outnumbered the Quechan warriors who gathered at Fort Yuma, which was now a center of trade with the Americans.

Simultaneously, the Mohave under Chief Arateve raided Cocopah territory after the Yuma asked them to join in the war.

[5] When conflict with the Cocopah ceased the Americans at Fort Yuma received a new objective which was to prevent further bloodshed between the native tribes.

War between the United States and the Mohave became a reality in 1858 when warriors attacked American settlers at Beale's Crossing in Arizona.