 Lieutenant Colonel John R. Baylor, who had led the 2nd Texas Mounted Rifles into New Mexico Territory one month earlier, defeated the Union garrison at the First Battle of Mesilla, proclaimed the area to be Confederate Arizona, and appointed himself its governor, sent patrols up the Rio Grande to keep watch on the Union posts at Fort Craig and Fort Stanton near the 34th parallel, the proposed northern border of the new territory.The Union Army, specifically the 3d Cavalry Regiment at Fort Craig, had launched a reconnaissance mission to guard against the approach of Confederate forces up the Rio Grande.The unit sent was a recently formed unit of New Mexican militia called Mink's Independent Cavalry Company.