on july 24, 1861, the secretary of war called on the governor of california for enlisted volunteer to guard the overland mail route from carson city to salt lake city. they were also to guard fort laramie. the initial call was for five companies of cavalry plus one regiment of infantry. on august 14, four more regiments of infantry and one regiment of cavalry were requested. they were to report to general edwin vose sumner. these volunteers replaced the regular troops transferred to the east before the end of 1861. california would have to protect itself using its own manpower during the civil war.