In January 1863, Colonel Patrick Edward Connor led a regiment of California Volunteers in a military campaign against the Shoshone tribe at Bear River in the Washington Territory. This operation was fueled by the escalating tensions between Native American tribes and settlers moving westward, largely driven by the discovery of gold and other resources. Connor's troops aimed to secure the region for American settlers and eliminate perceived threats from Indigenous peoples.

On January 29, the Volunteers arrived at a Shoshone village along Bear River, which was unprepared for an assault. Connor's forces launched a surprise attack, resulting in a deadly confrontation. The soldiers were able to inflict heavy casualties on the Shoshone, ultimately killing a significant number of individuals, including non-combatants. Estimates of the death toll vary, but it is suggested that hundreds lost their lives during the onslaught, including men, women, and children.

This massacre was part of a broader strategy by the U.S. government to quell Native American resistance as settlers expanded into their territories. The violence and tactics used during this engagement reflected the brutal nature of the conflicts that characterized this era in American history, revealing the complexities of westward expansion and its impact on Indigenous populations.