William "Frog" Edwards, only recently released from detention at Fort Yuma, ambushed a party of Union soldiers when they stopped at La Paz to purchase supplies.

The following year General James H. Carleton arrested several California secessionists bound for Texas and detained them at Fort Yuma; William "Frog" Edwards was one of these detainees.

On the evening of May 20, 1863, the Colorado River steamer Cocopah arrived at La Paz en route to Fort Mohave.

A small party of soldiers from the 4th California Infantry who were escorting the cargo disembarked to purchase supplies at Cohn's Store.

In response to Edwards' attack, a detachment of forty men from Fort Mojave commanded by Captain Charles Atchisson was deployed to hunt him down.