The New Mexico Campaign, a significant military operation of the trans-Mississippi theater of the American Civil War, unfolded from February to April 1862. This ambitious Confederate offensive aimed to seize the New Mexico Territory, which the Confederacy had claimed as its own Arizona Territory. The campaign was part of a broader Confederate strategy to control the American Southwest, gain access to valuable mineral resources in Colorado and Nevada,
and potentially open a route to the Pacific Ocean, with the ultimate intention of capturing California. The Confederate Army of New Mexico, primarily composed of Texans, marched west and north, seeking to establish Confederate dominance in a region far removed from the main battlefields of the East.
Confederate Ambitions and Sibley's Strategy
The Confederate strategy for the New Mexico Campaign was formulated by General Henry Hopkins Sibley, who presented his plan to Confederate President Jefferson Davis. Sibley envisioned an invasion along the eastern side of the Rocky Mountains, with the immediate goals of seizing the Colorado Territory, then experiencing a gold rush, and Fort Laramie, a crucial United States Army garrison along the Oregon Trail. Following these conquests, the plan called for turning westward to attack the mineral-rich territories of Nevada and California. Sibley's approach was to travel with minimal supplies, intending to sustain his forces by living off the land and capturing Union stockpiles at forts and depots along the Santa Fe Trail. Beyond the American territories, Sibley also intended to take the northern Mexican states of Chihuahua, Sonora, and Lower California, highlighting the expansive nature of the Confederate vision for the Southwest.
In December 1861, General Sibley, commanding the Army of New Mexico, issued a proclamation asserting Confederate possession of New Mexico. He urged citizens to abandon their allegiance to the Union and join the Confederacy, warning that those who cooperated with the enemy would face consequences. This proclamation set the stage for the Confederate advance, which began in February 1862, moving northward from Fort Thorn up the Rio Grande valley towards the territorial capital of Santa Fe and the Union storehouses at Fort Union. A detachment of 54 men was also sent to occupy Tucson, further demonstrating the Confederacy's territorial claims.
Key Engagements and Strategic Maneuvers
As Sibley's forces advanced, they followed the west bank of the Rio Grande, passing Fort Craig, which was garrisoned by a substantial 3,800-man Union force under General Edward Canby. Recognizing the danger of leaving such a large Union force in his rear, Sibley attempted to draw Canby's troops into battle on favorable terms. On February 19, Sibley camped east of Fort Craig, aiming to cut Union lines of communication with Santa Fe. The next day, Union forces advanced from the fort but were repelled by heavy Confederate artillery, forcing them to retreat. The Confederates then marched to Valverde Ford, six miles north of the fort, attempting to outflank the Union position. Canby attacked, but his forces were driven back by Confederates under Colonel Thomas Green, who took command after Sibley became indisposed. Despite the Union retreat to Fort Craig, Canby refused to surrender.
With only three days' rations, Sibley faced a critical decision: he could not attempt a siege of Fort Craig nor retreat to Mesilla. Instead, he chose to disengage and continue slowly northward towards Santa Fe, hoping to capture Union supplies there and cut Fort Craig's supply and communication lines. The Battle of Valverde had taken a toll, with the loss of horses forcing the 4th Texas to dismount and the remaining horses, already weakened, distributed among other units. The Confederates also lost much of their transportation, necessitating the carrying of wounded, which significantly slowed their advance. Meanwhile, Canby disbanded his militia and most volunteer units, sending mounted units north to act as partisans, obstruct Sibley's movements, and cut off his supplies by removing cattle, grain, and other provisions from his route.
The Turning Point at Glorieta Pass and Confederate Retreat
The slow Confederate advance proved costly. They reached Albuquerque on March 2 and Santa Fe on March 13, but their delayed arrival meant they failed to capture most of the Union supplies in those cities. This delay also allowed Union reinforcements from Colorado, under Colonel John Slough, to reach Fort Union. Slough, claiming seniority over Paul, who was then in command of the fort, took charge. Despite Canby's earlier orders to Paul not to move from Fort Union until advised of a junction point, Slough advanced with 1,342 men from the garrison. Canby, upon learning of the command change, instructed Slough to advise him of his plans and movements for cooperation and to harass the enemy through partisan operations, obstructing their movements and cutting off supplies.
The Union and Confederate forces clashed at the Battle of Glorieta Pass on March 28. While the Confederates managed to push the Union force through the pass, their victory was short-lived. A detachment of the 1st Colorado Infantry, under Major John M. Chivington, destroyed the Confederate wagon train, which contained nearly all of their supplies and ammunition. This devastating loss forced Sibley to pull his army back to Albuquerque, awaiting reinforcements from Texas that never materialized. Slough, receiving orders from Canby to return immediately to Fort Union, also retreated, fearing a court-martial if he disobeyed. Upon his arrival at the fort, Slough resigned his commission and returned to Colorado, leaving Lieutenant Colonel Samuel Tappan in command of the regiment and Paul once again in command of the fort. The destruction of their supply train at Glorieta Pass effectively broke Confederate power in the New Mexico Territory, forcing their withdrawal and marking the end of their ambitious campaign to control the American Southwest.
