Howdy,
I saw a reference to two skirmishes in California on the Civil War Battle Page at www.fortunecity.com/victorian/pottery/1080/ when he still had state listings. However, I don't remember the names they were listed under, and unfortuantely the state listings have been dropped.
What might be interesting to recall is that the Territory of Arizona seceded (part of New Mexico and Arizona south of the 34th parallel) from the US and joined the Confederacy. Some interesting reading is at http://azrebel.tripod.com/page5.html . This site list the western most battle as Picadio Pass, Az, 15 April 1862.
Also, had Sibley not failed in his New Mexico campaign (that territory above the 34th parallel) things could have been quiet different in the west and the pro southern faction in the southern part of California possibly might have tried to break away. The two significant battles in New Mexico were Valverde on 26 Feb 1862 and Glorietta Pass on 28 Feb 1862. The Conferates carried both but allowed Union forces to get in their rear and destroy their wagon train following the battle of Glorietta Pass forcing them to abandon New Mexico. One of my Great Great Uncles was in the 7th Texas Cavalry and was said to have talked about almost dying of thirst during Sibley's retreat back to Texas.
There was also an interesting article in one of the Civil War magazines a few years back that made the argument that the Union did not win the war in the east, that the south lost the war in the west. This article stated that Jefferson Davis did not have another general he trusted with which to replace Albert S. Johnston, and of course Davis and Joe Johnston had a feud dating back to their West Point days. Pemberton used this to be openly insubordiante and took his army into Vicksburg against Johnston's direct orders not to become intrapped in the city. Had the south managed to have stopped Grant in the west he might not have risen to over all command and the north did not seem to have another general who could/would stay engaged with Lee.
Bobby