Lieutenant Pettis arrived in San Francisco about the fifteenth of October, and immediately commenced business by opening his recruiting office on the corner of Montgomery and Clay streets, in the same building with the _Morning Call_. He was successful, as by the fifteenth of January he had recruited and sent to the regiment one hundred and two men, and was ordered by General George Wright, then commanding the department of California (and who was afterwards lost on the steamer "Brother Jonathan" on his way to Oregon), to close his office and join his regiment at Camp Latham. In the meantime, four companies of the regiment, under Major E. A. Rigg, had proceeded to Fort Yuma, on the Colorado river, and relieved the regulars who were there. Captain Winfield Scott Hancock, Assistant Quartermaster United States Army, had also been relieved and ordered to the States. He had been on duty at Los Angeles. Three companies of the regiment had been ordered to Warner's Ranch, about half way between Los Angeles and Fort Yuma, and established Camp Wright. On the twelfth of February, orders had been received by Colonel J. H. Carleton, commanding the regiment, to form the tenth company of his regiment from the recruits enlisted in San Francisco by Lieutenant Pettis. Company K, First Infantry, California Volunteers, was thus formed, and was officered as follows: Captain, Nicholas S. Davis, promoted from First Lieutenant of Company A; First Lieutenant, George H. Pettis, promoted from Second Lieutenant of Company B; Second Lieutenant, Jeremiah Phelan, appointed from Hospital Steward of the regular army.
In the meantime, the government at Washington had received information that General H. H. Sibley had left San Antonio, Texas, with about three thousand seven hundred rebel soldiers for New Mexico, and as the government had immense stores of clothing, camp and garrison equipage, and commissary stores in different posts in that Territory and Arizona, with but few troops to defend them, and a majority of the officers avowed secessionists, the rebels expected an easy conquest. Accordingly, Colonel Carleton had orders to organize what was known as the "California Column," which consisted of the First and Fifth Infantry, California Volunteers, (George W. Bowie was Colonel of the Fifth Infantry, California Volunteers); First Battalion Cavalry, California Volunteers; Company B, Captain John C. Cremoney, Second Cavalry, California Volunteers, and Light Battery A, Third United States Artillery, Captain John B. Shinn.