Sibley's New Mexico Campaign

• Brigadier General Henry Hastings SibleyValverde
• Colonel Tom GreenValverde
• Major Charles L. PyronGlorieta Pass
• Lieutenant Colonel William R. ScurryGlorieta Pass

• Colonel E. R. S. CanbyValverde
• Major John ChivingtonGlorieta Pass
• Colonel John P. SloughGlorieta Pass

Confederate

Brigadier General Henry Hopkins Sibley commanded the Confederate Army of New Mexico. Under him served the 4th Texas Mounted Rifles and the 5th Texas Mounted Rifles, each fielding a battery of mountain howitzers, along with five companies drawn from the 7th Texas Mounted Rifles and six companies belonging to the 2nd Texas Mounted Rifles, the latter supported by an artillery battery of its own. Rounding out the force were several companies of Arizona Confederate mounted volunteers.

Once Sibley reached New Mexico that January, he consolidated his artillery pieces into a single battalion, placing Captain Trevanion Teel at its head and elevating him to the rank of major. Toward the close of February, five more companies from the 7th Texas joined the army and took up garrison duty at Fort Thorn near Mesilla.

Confederate strategy

For a considerable time, people living in the southern reaches of the New Mexico Territory had grown frustrated that the territorial capital in Santa Fe sat too remote to address their needs adequately. When Regular army troops pulled out as the war began, this only reinforced local suspicions that they had been left to fend for themselves. In March 1861, gatherings held in Mesilla and Tucson resulted in votes to align that territory with the Confederacy, and local militia units were organized for self-defense. Come July 1861, Lieutenant Colonel John Baylor marched a battalion of Texas mounted rifles into the region, occupying Mesilla and driving back Union forces from Fort Fillmore during what became known as the First Battle of Mesilla. Following this success, Baylor set up the Confederate Territory of Arizona in the land below the 34th parallel.

The campaign that unfolded in 1862 built directly upon this earlier approach, one that Sibley had outlined in a proposal delivered to Confederate president Jefferson Davis. Under Sibley's vision, Confederate forces would push northward along the eastern flank of the Rocky Mountains, capturing the Colorado Territory during its Gold Rush boom along with Fort Laramie, recognized as the key United States Army post along the Oregon Trail, before pivoting west toward the resource rich lands of Nevada and California. His approach favored traveling light, relying on the countryside itself for sustenance while seizing supply caches held at Union forts and depots scattered along the Santa Fe Trail. After securing these territories, Sibley envisioned extending Confederate control into Mexico's northern states, Chihuahua, Sonora, and Lower California, achieved through either purchase agreements or outright military conquest.

March toward Santa Fe

General Sibley declared on December 20, 1861, that his Army of New Mexico now held the territory for the Confederate States. His proclamation urged residents to break their ties with the Union and throw in with the Confederacy, cautioning that anyone aiding the enemy would face consequences and share in whatever fate befell that enemy. The following February, Sibley pushed his troops northward from Fort Thorn along the Rio Grande, aiming for Santa Fe and the supply depots waiting at Fort Union. Before continuing, he split off 54 soldiers to seize Tucson. His main body moved up the river's western bank past Fort Craig, where Canby commanded a Union garrison numbering 3,800. Aware that leaving such a sizable force at his back would be dangerous, Sibley sought to draw Canby's men into an engagement he could win.

By February 19, Sibley had set up camp among sandhills east of the fort, hoping to sever the Union's communication routes to Santa Fe. When Union troops marched out from the fort the next day, Confederate artillery fire drove them back inside. The following day, Confederate forces pushed toward Valverde Ford, located six miles north of the fort, attempting to flank their opponents. Canby launched an assault there, yet his men were repelled by Confederates under Colonel Thomas Green, who had assumed command since Sibley was unwell, and rumors suggested drunkenness played a part. Though beaten back to Fort Craig, Canby's forces refused to give up the fight.

With supplies for only three more days, Sibley found himself unable either to besiege the fort or retreat toward Mesilla. He instead pulled away from Fort Craig and pressed on gradually toward Santa Fe, still hoping to seize supplies there while simultaneously severing the fort's own supply lines. Losses of horses during the Valverde fighting forced the 4th Texas to fight on foot, its surviving mounts, already weak, handed over to other units. The heavy toll on their wagons and transport at Valverde meant the wounded had to be carried along, further slowing the march. Meanwhile Canby worked to trap Sibley's army in a pincer between his own men and Fort Union. He dissolved his militia units along with most volunteer companies, dispatching the bulk of his cavalry north to harass the Confederates, disrupt their movement, and strip the countryside of cattle, grain, and any resources that might sustain the invading force.

The Confederate march resumed on February 23, bringing them to Albuquerque by March 2 and to Santa Fe by March 13, though their sluggish pace meant most Union stores at both locations had already been moved beyond reach. This delay also gave time for Colonel John Slough to bring reinforcements down from Colorado to Fort Union, then held by Paul. Because his commission as colonel predated Paul's promotion to the same grade, Slough asserted the right to take charge of the post. Canby had previously instructed Paul to remain at Fort Union until told where and how their forces should join. Once informed that command had shifted to Slough, Canby asked to be kept apprised of his plans so their efforts might align, while also directing him to strike at the Confederates through partisan tactics, block their advance, and choke off their supplies. Slough then set out from the fort leading 1,342 men.

The two armies clashed at Glorieta Pass on March 28. Confederate troops managed to force the Union line back through the pass, but were compelled to withdraw after their wagon train, carrying nearly all their ammunition and provisions, was destroyed. Sibley withdrew to Albuquerque to wait for reinforcements arriving from Texas. Slough, under orders from Canby to return at once to Fort Union, complied as well, worried that ignoring the command might bring a court martial. Upon reaching the fort he stepped down from his commission and headed back to Colorado, leaving Lieutenant Colonel Samuel Tappan to lead the regiment while Paul resumed his post in charge of the fort.

Aftermath

After the Confederates withdrew, Colonel James Carleton led elements of the California Column into western Texas, where they took possession of several forts. Canby received a promotion to brigadier general and was sent east to serve. Carleton took his place as head of the department and likewise earned a promotion to brigadier general. Volunteers from New Mexico were organized into the 1st New Mexico Cavalry, placed under the leadership of Kit Carson, and this regiment spent the remainder of the conflict battling Native tribes within the territory.

Confederate leaders still regarded Arizona as belonging to their nation, and they drew up multiple schemes for a second invasion, yet none of these plans ever came to fruition. Sibley's command earned the nickname "Arizona Brigade" among many, and it went on serving in different parts of Texas and Louisiana for the rest of the war. As for Sibley himself, he was demoted in 1863 to overseeing supply trains.