Soon after the American Civil War erupted, Confederate officials began making plans to annex the New Mexico Territory and to extend their authority to the Pacific Ocean via California. As early as June 1861, Lieutenant Colonel John Baylor led a small band of Rebel soldiers out of Central Texas toward El Paso and subdued Fort Bliss on July 1. From there, he marched 300 miles up the Rio Grande River into New Mexico and forced the evacuation of Fort Fillmore on July 26. Five days later, Baylor, apparently satisfied with the extent of his conquest, trumpeted the establishment of the Arizona Territory and appointed himself as the governor.
Department of New Mexico
In response to Baylor’s actions, on November 9, 1861, the United States War Department issued General Orders No. 97, creating the military Department of New Mexico, “to consist of the Territory of New Mexico—to be commanded by Colonel E.R.S. Canby, U.S.A.” Hoping to prevent a deeper Confederate thrust into the territory, Canby established his departmental headquarters at Fort Craig, near the Rio Grande, nearly 170 miles north of the Texas border. He then set about recruiting volunteers to repel the Confederate intruders.
Alarmed by the invasion of their homeland, many native New Mexicans rallied to join the Union volunteer army. As news of a second invasion became more certain, Canby requested the territorial governor of Colorado, William Gilpin, on January 1, 1862, to send, “as large a force of the Colorado Volunteers as can possibly be spared” to assist in defending the New Mexico Territory.
Second Confederate New Mexico Campaign
The second Confederate offensive against New Mexico began when Brigadier General Henry Hopkins Sibley led his Army of New Mexico (also known as Sibley’s Brigade) out of Texas in early 1862. Sibley’s force comprised roughly 2,600 soldiers from the 4th, 5th, and 7th Texas Volunteer Cavalry. Sibley’s broad objectives were to:
- subdue the remaining Union garrisons in New Mexico,
- seize their supplies,
- travel up the Santa Fe Trail and capture the Colorado gold fields,
- head west to conquer California.
Battle of Valverde
As Sibley entered New Mexico, Canby concentrated his forces at Fort Craig, just south of Socorro. On February 21, led by Lieutenant Colonel William R. Scurry, Canby’s volunteers engaged Sibley’s raiders at the Battle of Valverde, near Fort Craig. During the engagement, the Rebels launched a frontal assault that breached the Union lines and forced the Federals to fall back to Fort Craig.
Sibley Occupies Albuquerque
Rather than pressing the conflict, Sibley bypassed Fort Craig and continued to march north along the Rio Grande, leaving Canby isolated from the rest of his department. With little opposition in front of him, Sibley occupied Albuquerque on March 2, 1862, and the territorial capital at Santa Fe on March 10.
Sibley’s next objective was to subdue Fort Union, a major federal supply depot next to the Santa Fe Trail in northern New Mexico. Upon learning of Canby’s isolation at Fort Craig in February, Colonel Gabriel R. Paul assumed command of the federal forces at Fort Union. On March 10, Colonel John P. Slough arrived at the fort leading 950 soldiers of the 1st Regiment of Colorado Volunteers to reinforce the existing garrison of 850 men. Being senior in command, Slough assumed command from Paul.
March 22 – Slough Pursues Sibley
Almost immediately, Slough and Paul disagreed about how to deal with Sibley. Paul urged Slough to follow Canby’s latest orders to stay put and to defend Fort Union. Slough favored marching toward Santa Fe to engage the Confederates on the battlefield. Being in command, Slough prevailed. On March 22, 1862, he led 1,300 men out of Fort Union, headed toward Sibley’s headquarters at Santa Fe. As Slough headed west, Sibley dispatched Major Charles Pyron’s Fifth Texas Regiment east along the Santa Fe Trail toward Fort Union.
March 25 – Conflict at Glorieta Pass
By March 25, both armies were near Glorieta Pass, a gap in the Sangre de Cristo Mountains southeast of Santa Fe. The next day, nearly 400 Federals, commanded by Major John M. Chivington, engaged about 300 Rebels, led by Major Charles L. Pyron at Apache Canyon on the west end of the pass. After outflanking his opponent several times, Chivington ordered a frontal attack that scattered the Confederates and forced them to retreat from the pass. Chivington then settled down and awaited Slough and the main Union force.
March 27 – Both Sides Reinforce
March 27 saw no fighting, as both sides reinforced. By the end of the day, Slough had rejoined Chivington, bringing the number of Union soldiers available for combat to approximately 1,300. The Confederates, led by Lieutenant Colonel William R. Scurry, fielded nearly 1,100 men.
March 28 – Both Sides Attack
On the morning of March 28, 1862, both commanders ordered an assault. As Scurry moved his men east through Glorieta Pass to engage the Federals, Slough divided his army. The Union commander ordered two infantry battalions, totaling nearly 400 men, under the direction of Chivington, to circle around the Rebels as they advanced and to hit them in the flank. As the Texans—who now enjoyed a numerical advantage—advanced through the pass, Slough attacked with the rest of his force at approximately 11 a.m. The two sides fought for nearly five hours. Gradually, the Confederates pushed Slough’s forces eastward before forcing the Federals to retreat, leaving the Rebels in possession of the field by sundown.
Federals Burn Confederate Supply Train
Unbeknownst to Scurry, while he was winning the battle, he was losing the campaign. By the time Chivington arrived to attack Scurry’s flank, the Texans had advanced so far through the pass that they exposed their rear. At the urging of two regular army captains, William H. Lewis and Asa B. Carey, Chivington ordered an assault on Scurry’s supply train. The Federals sacked and burned roughly eighty wagons of stores and ammunition, spiked several pieces of artillery, and drove off hundreds of horses and mules before rejoining Slough.
Slough and Scurry spent the next day assessing their losses and burying their dead. The Union suffered about 122 casualties (thirty-eight killed, sixty-four wounded, and twenty captured). The Confederacy lost 121 soldiers (thirty-six dead, sixty wounded, and twenty-five captured). Without supplies and ammunition, any further advance against Fort Union was out of the question, so Scurry retreated to Santa Fe on March 31, to rejoin Sibley.
With Canby still at his rear and having no means to sustain his army in hostile territory, Sibley began withdrawing from New Mexico. After Sibley’s retreat, Canby resumed control of all the troops in his department. When Slough returned to Fort Union in early April, Canby charged him with disobeying orders for leading the expedition to Glorieta Pass, despite the success of his operation. On April 9, 1862, Slough resigned his position with the Colorado unit and moved east, where he eventually became a brigadier general in the volunteer army.
On April 14, 1862, while pursuing the retreating Texans, Canby’s troops surprised a Confederate regiment encamped near the village of Peralta, roughly twenty miles south of Albuquerque. Although there were few casualties, the federals captured more of Sibley’s dwindling supplies in this last engagement of the New Mexico Campaign.
By July, all the Texans had evacuated the territory, and New Mexico remained in Union control for the duration of the war. Because it was the decisive turning-point of the Civil War in the Far Western Theater, many historians refer to the Battle of Glorieta Pass as the Gettysburg of the West.