The Civil War in New Mexico
The vast expanse of the New Mexico Territory, a land of stark beauty and untapped resources, found itself caught in the crosscurrents of the American Civil War. While geographically distant from the major battlefields of the East, New Mexico became a crucial theater in the struggle for control of the West. This article explores the complex events that unfolded in the region, from secessionist sentiments to ambitious Confederate campaigns, and the pivotal battles that ultimately determined the fate of the territory.
Before the eruption of the Civil War, simmering discontent brewed in the southern reaches of the New Mexico Territory. Residents felt neglected by the territorial government in Santa Fe, perceiving it as too remote to adequately address their local concerns. The withdrawal of regular Union troops at the onset of the war only exacerbated this sense of abandonment. Consequently, a secession convention convened in Mesilla in March 1861, where citizens overwhelmingly voted to join the Confederacy, forming militia companies to defend their decision. The stage was set for conflict in The Civil War in New Mexico.
With Union forces largely absent from the southern part of the territory and neighboring Texas firmly in Confederate hands, the 2nd Texas Mounted Rifles, under the command of Lieutenant Colonel John R. Baylor, were dispatched to occupy the abandoned forts along the western Texas frontier and advance into New Mexico. Their mission was to seize Union forts along the Rio Grande, effectively extending Confederate control over the region.
About six miles southeast of Mesilla lay the small, unassuming post of Fort Fillmore. Originally established to manage relations with the local Apache tribes, the fort had gradually fallen into disrepair, its garrison reduced. However, as tensions escalated and news of the approaching Texans reached Union ears, reinforcements were hastily sent to bolster the fort’s defenses.
First Battle of Mesilla
On July 24, 1861, a contingent of 250 soldiers from the 2nd Texas Mounted Rifles crossed the Rio Grande and entered Mesilla. They were greeted by enthusiastic cheers from the town’s inhabitants, many of whom were ardent Confederate sympathizers. Soon after, a company of Arizona Confederates joined Baylor’s forces. Baylor planned to launch an assault on Fort Fillmore the following day, but his plans were compromised when a Confederate deserter divulged the information to Major Isaac Lynde, the fort’s commander.
Major Lynde, determined to confront the Confederate threat, left a small detachment to guard Fort Fillmore and marched on Mesilla with approximately 380 Union troops on July 25. Upon reaching the town, he demanded Baylor’s unconditional surrender. The Confederates, defiant, refused. The Union forces opened fire with their mountain howitzers, and infantry was ordered to advance. The attack was hampered by the heavy sand and cornfields surrounding the town. Lynde then ordered his cavalry and three companies of Mounted Rifles to charge the Confederate lines.
The Confederates successfully repulsed the initial Union assault, and a long-range skirmish ensued between the opposing forces. After three Union soldiers were killed, and two officers and four other men were wounded, Major Lynde ordered a retreat back to Fort Fillmore. The First Battle of Mesilla resulted in a Confederate victory, bolstering their control over the southern part of the territory.
As night fell on July 26, Baylor ordered his artillery and more cavalry to reinforce his position, while the remainder of his command prepared to attack Fort Fillmore the next day. That same night, Baylor’s men managed to capture 85 of the fort’s horses, significantly crippling the fort’s transportation capabilities. Anticipating an imminent attack, Major Lynde made the fateful decision to destroy the fort’s ammunition and supplies, and ordered a retreat northeast towards Fort Stanton, located approximately 150 miles away.
The following day, July 27, the Confederates pursued the retreating Union forces, capturing several stragglers along the way. They soon overtook Lynde’s command, which had been reduced to about 100 men, as they crossed the arid Organ Mountains. The captured Union soldiers were paroled, and Baylor returned to Fort Fillmore.
The Battle of Mesilla had far-reaching consequences. It officially established the Confederate Territory of Arizona, encompassing the southern portion of the New Mexico Territory and the present-day state of Arizona. It also paved the way for the ambitious Confederate New Mexico Campaign the following year.
In August 1861, Baylor solidified Confederate control by establishing the Confederate Arizona Territory, installing himself as its military governor, designating Mesilla as the capital, and declaring martial law.
Second Battle of Mesilla
Less than a year later, in June 1862, another clash occurred near Mesilla between Arizona rebels and the New Mexican Militia. This engagement, known as the Second Battle of Mesilla, resulted in a Union victory, although remarkably, neither side suffered any casualties. However, the Confederate forces sustained losses in supplies and horses, forcing them to retreat. The rebels officially withdrew from Mesilla a few days later, on June 7. This marked the last engagement between Union and Confederate forces in the Confederate Arizona Territory.
Sibley’s New Mexico Campaign (February-March 1862)
Under the leadership of Confederate Brigadier General Henry Hopkins Sibley, southern troops launched an invasion of northern New Mexico Territory in February 1862. Their objective was to seize control of the American Southwest, the goldfields of Colorado, and the ports of California. This ambitious Confederate campaign in the Trans-Mississippi Theater aimed to establish control of the American West and open a new front in the war.
In the spring of 1861, Sibley, a Louisianan who had recently resigned from the U.S. Army, met with Confederate President Jefferson Davis and presented a strategic plan to conquer the American West. The plan involved an invasion along the eastern side of the Rocky Mountains, seizing Colorado Territory at the height of a gold rush, and capturing Fort Laramie, Wyoming, the most important garrison along the Oregon Trail.
Sibley then intended to focus on areas farther west, targeting the mineral-rich regions of Nevada and California. His strategy also included acquiring or invading the northern Mexican states of Chihuahua, Sonora, and Lower California.
To make this highly ambitious plan feasible, Sibley adopted a strategy of carrying minimal supplies, relying on capturing supplies from Union forts and depots along the Santa Fe Trail, and living off the land. He also intended to recruit new soldiers along the way, confident that there was substantial Confederate sentiment and potential for cooperation in the sparsely defended territories. This was all part of The Civil War in New Mexico.
President Davis approved the plan and granted Sibley a brigadier general’s commission.
Leading a force of over 2,000 troops, Sibley departed from San Antonio, Texas, in November 1861, stopping in El Paso to recruit additional soldiers. They then marched towards Mesilla, the Confederate capital of Arizona Territory. On December 20, 1861, now in command of the Army of New Mexico, Sibley issued a proclamation claiming possession of New Mexico in the name of the Confederate States. He called on the citizens to abandon their allegiance to the Union and join the Confederacy, warning that those "who co-operate with the enemy will be treated accordingly, and must be prepared to share their fate."
In February 1862, Sibley led his men northward up the Rio Grande Valley towards the territorial capital of Santa Fe and the storehouses at Fort Union. Sibley’s initial objective was to capture Fort Craig, New Mexico.
Battle of Valverde
As the Confederates advanced across and up the east side of the Rio Grande towards the ford at Valverde, north of Fort Craig, their goal was to sever Federal communications between the fort and military headquarters in Santa Fe. However, on February 20, 1862, approximately 3,000 Union troops, led by Colonel Edward Richard Sprigg Canby, left Fort Craig to prevent the estimated 2,500 Confederates from crossing the river. When the Union forces were positioned opposite the Confederates across the river, Canby opened fire and sent the Union Cavalry over, forcing the Rebels back. The Confederates halted their retreat at the Old Rio Grande riverbed, which provided an advantageous defensive position. After deploying all his men, Canby determined that a frontal assault would likely fail and instead planned to assault and turn the Confederate left flank. However, before he could execute this plan, the Rebels launched an attack. The Union forces successfully repelled a cavalry charge, but the main Confederate force launched a frontal assault, capturing six artillery pieces, causing the Union battle line to break, and prompting many Federal troops to flee. Canby then ordered a retreat.
In the midst of the battle, Confederate reinforcements arrived, and Sibley was preparing to order another attack. After two days of intense fighting, Canby requested a truce, signaled by a white flag, to remove the bodies of the dead and wounded. With the Confederates in possession of the battlefield, they claimed victory. However, they had suffered heavy casualties, estimated at 187. The Union also suffered an estimated 202 casualties.
Despite the Confederate victory, Sibley concluded that he had lost too many men and supplies to successfully capture Fort Craig. He decided to bypass the fort and head north towards Albuquerque, where the Federals had stored an estimated $250,000 worth of goods. Departing from Valverde on February 23, they reached Albuquerque on March 2. However, no battle ensued, as the defenders and supplies had already been evacuated.
The Confederate troops continued their slow advance through the imposing peaks and buttes of the Jemez and Sangre de Cristo mountains towards Santa Fe. However, their progress was significantly slowed by the loss of many horses at Valverde, forcing many soldiers to march on foot. They had also lost much of their transportation during the battle, which caused them to carry the wounded. Despite these challenges, they continued northwestward, reaching Santa Fe on March 13. Sibley detached 600 men to plunder the city, but once again, they found no federal ammunition or supplies. Sibley’s men then headed towards Fort Union, located approximately 90 miles northeast of Santa Fe.
Meanwhile, the Confederates’ slow advancement allowed reinforcements from Colorado, under the command of Colonel John Slough, to reach Fort Union. Slough, the senior officer at the fort, assumed command and reported to Colonel Edward Canby at Fort Craig. Canby instructed Slough to "harass the enemy by partisan operations, obstruct his movements, and cut off his supplies." Slough interpreted this as authorization to advance. He soon gathered 1,342 men from Fort Union and began the trek to Santa Fe. The Civil War in New Mexico was not yet over.
Battle of Glorieta Pass
The Battle of Glorieta Pass proved to be a decisive turning point in the New Mexico Campaign. In late March 1862, Union forces clashed with Confederate troops in the strategically important Glorieta Pass, located east of Santa Fe. The Confederates initially gained the upper hand, but a daring Union raid on their supply train crippled their ability to sustain the campaign. Deprived of vital supplies and facing increasing resistance, Sibley was forced to order a retreat back to Texas, effectively ending the Confederate threat to New Mexico. The impact of The Civil War in New Mexico would be felt for decades to come.
©Kathy Alexander/Legends of America, updated March 2025.