The 5th United States Infantry was stationed in New Mexico when on June 1st 1863 it officially got its new Colonel; Union Major General John F Reynolds, he would not take command.
The 5th United States Infantry traces its origins back to 1808, however technically the regiment was created March 3rd 1815 by an Act of Congress reducing the Regular Army from 46 infantry and 4 rifle regiments with the ending of the War of 1812, to peace time numbers of 8 infantry. Six old regiments were consolidated into the 5th, and placed under command of Colonel James Miller.
In the spring of 1861 when the Civil War got started, the 5th was ordered to concentrate at Albuquerque, New Mexico for a move east. But, with some Western Departmental pressure placed on Washington, DC, the 5th was left on the frontier. When Confederates from Texas invaded New Mexico in early 1862, four companies of the 5th were the rear Union guard at Valverde on February 21st 1862, in which the Confederates were victorious. Two other companies captured a field piece on March 28th 1862 at the Battle of Glorieta Pass, defeating the Confederates.
On June 1st 1863 the 5th received a new Colonel, Union Major General John F Reynolds. He was of course on detached service commanding volunteers with the Army of the Potomac, and was killed one month later at the Battle of Gettysburg. After Reynolds’ death the army appointed another Army of the Potomac general, Daniel Butterfield to be the Colonel of the 5th, but he also was wounded at the Battle of Gettysburg, and would not join the regiment while the war was going on.
The 5th would remain throughout the Civil War on frontier duty watching for another Confederate attack. After the war ended the 5th was transferred to the east moving to Fort Riley in Kansas.