As the California Volunteer regiments formed, some were sent south with Colonel George Wright, commanding officer of the District of Southern California. He was to replace the Federal troops in Los Angeles, gathered there to prevent a rising by the numerous secessionist sympathizers in Southern California. In October 1861, Wright was promoted to Brigadier General of Volunteers and placed in command of the Department of the Pacific, replacing Sumner who had recommended Wright as his replacement. Colonel James Henry Carleton of the 1st California Volunteer Infantry Regiment replaced Wright as commander in the south. Detachments were soon sent out by Carleton to San Bernardino and San Diego Counties to secure them for the Union and prevent the movement of men, horses and weapons eastward to the Confederacy.