In OR near which city did the westernmost civil war battle TAKE place?

The westernmost battle of the American Civil War took place near the city of Santa Rosa, California. This battle, known as the Battle of Santa Rosa, occurred on March 21, 1865, and was part of the larger conflict in California, which was primarily focused on maintaining Union control in the region. While not one of the most significant battles of the war, it marked the farthest west engagement in the conflict.