Battle of Glorieta Pass

Confederate strategy in the Southwest rested on Brigadier General Henry Hopkins Sibley's proposal to march a brigade of Texas mounted volunteers up the Rio Grande, take the territorial capital, and continue to the Colorado goldfields and eventually to California. Sibley received authorisation in the summer of 1861 and assembled roughly 2,500 men at San Antonio over the following autumn.

The brigade entered New Mexico in February 1862. At the Battle of Valverde on 21 February it fought Colonel Edward R. S. Canby's regulars and territorial volunteers to a costly tactical victory, but failed to take Fort Craig, which sat astride Sibley's line of communication and held the supplies his men badly needed. Sibley chose to bypass the fort. His troops occupied Albuquerque on 2 March and Santa Fe on 13 March, finding both towns largely stripped of the stores they had counted on capturing.^[2]

That left Fort Union, roughly ninety miles northeast of Santa Fe on the Santa Fe Trail, as the only depot in the territory worth taking. It also left the Confederate column at the end of a supply line running back to Texas, in a territory that could not feed it.

Word of the invasion reached Denver in February. The 1st Colorado Volunteer Infantry, recruited largely from the mining camps and known to itself as the Pike's Peakers, left Camp Weld on 22 February and covered the distance to Fort Union in thirteen days, marching the last stretch in bitter weather. Colonel Slough, a Denver lawyer with a talent for antagonising his own officers, took command of the combined force at the fort on 11 March.

Canby's orders to the Fort Union garrison were to stand on the defensive until he could bring his own column up from Fort Craig. Slough read them as permissive, and on 22 March marched southwest with about 1,340 men — the Colorado regiment, two companies of the 5th U.S. Infantry, detachments of the 1st and 3rd U.S. Cavalry, and two batteries. Whether he exceeded his instructions was argued over for the rest of his life.^{[citation needed]}

On the Confederate side, Major Charles L. Pyron moved out from Santa Fe on 25 March with about 300 men, camping at Johnson's Ranch at the western mouth of the pass. Scurry followed with the bulk of the 4th and 7th Texas Mounted Volunteers. Sibley remained at Albuquerque and was not present at any point in the battle, an absence his officers commented on afterwards in terms that did not improve his reputation.^[3]

Slough sent Chivington ahead on 26 March with about 400 men to scout the pass. Early in the afternoon the advance ran into Pyron's pickets in Apache Canyon, at the eastern end of the pass, and took a number of prisoners before the Confederate guns opened on them from a narrow point in the canyon.

Chivington pulled his infantry up onto the slopes on both sides of the trail and worked them forward above the Confederate position, which was strong from the front and nearly untenable once fire came down from the rim. Pyron fell back about a mile and a half to a second position behind a broken bridge over an arroyo. Captain Samuel Cook's company of Colorado cavalry jumped the gap under fire and rode into the Confederate line from the flank, and the position collapsed.

Pyron withdrew to Johnson's Ranch after dark. The Union lost 5 killed and 14 wounded; Confederate losses were about 4 killed, 20 wounded and 71 captured. It was a small action, and it was also the first clear Union success of the campaign, which mattered more to the Colorado volunteers than the numbers suggest.

Neither side pressed the other on 27 March. A truce was agreed to collect the wounded and bury the dead from Apache Canyon, and both commanders spent the day being reinforced. Scurry came up to Johnson's Ranch that night with the rest of the brigade, bringing the Confederate force in the pass to roughly 1,100 men and three guns. Slough moved his main body forward to Kozlowski's Ranch, about six miles east of Pigeon's Ranch, and camped.

Both commanders decided independently to attack on the morning of 28 March, and both left their supply trains behind — Scurry at Johnson's Ranch with a guard of about 200, mostly teamsters and men detailed from the sick; Slough at Kozlowski's, which was never threatened.

Slough divided his command before dawn. About 430 men under Chivington were sent south to cross Glorieta Mesa under the guidance of Lieutenant Colonel Manuel Antonio Chaves, with orders to come down on the Confederate flank or rear. Slough took the remaining 900 west along the trail and halted at Pigeon's Ranch — a Santa Fe Trail stage stop of some thirty rooms kept by Alexander Valle — to water the horses.

Scurry's column arrived while the Union force was strung out along the road. The fighting that developed lasted five to six hours and moved eastward in three stages as the Union line was forced back: first from a position west of the ranch buildings, then from the ranch itself, and finally to a ridge about a mile and a half east of it. The Confederates attacked repeatedly on both flanks and through the centre, taking heavy losses from the Union batteries at close range; Scurry had two horses shot under him and was grazed in the face.

By late afternoon Slough had pulled back to Kozlowski's Ranch in good order. Scurry, whose men were exhausted and out of water, sent a request for a truce to bury the dead, which Slough accepted. The Confederates held the field, and the ranch buildings, and the road.^[4]

Chivington's detachment spent the morning working along the top of Glorieta Mesa and by early afternoon was standing above Johnson's Ranch, looking down at the entire Confederate train: between seventy and eighty wagons, several hundred horses and mules, the brigade's ammunition and rations, and a single gun.

The descent was steep enough that some of the men were let down on ropes. The guard was scattered after a brief resistance; the Union party spent several hours burning the wagons, spiking the gun and bayoneting or driving off the animals, then climbed back over the mesa and rejoined Slough that night. There were no Union deaths in the action.

The scale of the loss is what decided the campaign. Scurry's brigade had won the fight at Pigeon's Ranch and had, by that evening, no rations, no ammunition beyond what the men carried, no tents and no transport, in mountain country in March, at the end of a supply line running six hundred miles to San Antonio.^[5] Whether Chaves proposed the route or merely guided it has been disputed by his descendants and by Chivington's, at some length and without resolution.

Casualty returns for the three days are inconsistent and were compiled by both sides in circumstances that did not favour precision. Union losses are usually given as about 51 killed, 78 wounded and 15 missing or captured; Confederate losses as about 48 killed, 80 wounded and 92 captured, though Scurry's own report and the Union burial details do not agree on the dead.

Scurry held his position through 29 March and then withdrew to Santa Fe. Sibley began the retreat down the Rio Grande in early April, was blocked at Peralta by Canby on 15 April, and took his surviving troops on a punishing detour west of the river through the San Mateo Mountains to avoid another engagement. The brigade reached Fort Bliss at the beginning of May having lost, over the campaign, something close to a third of its strength to combat, disease and desertion. The last Confederate units left New Mexico in July.

No further Confederate attempt was made on the Southwest. The California Column under Colonel James Henry Carleton reached the Rio Grande in the summer of 1862 and found no enemy in the territory. Slough resigned his commission within weeks of the battle after a bitter dispute with his own officers, and Chivington — promoted on the strength of the supply train raid — went on to command at Sand Creek two years later, which is now the larger part of what he is remembered for.

Much of the ground fought over on 28 March is now within the Glorieta Unit of Pecos National Historical Park, which took in the Pigeon's Ranch and Johnson's Ranch sites in the early 1990s. Two of the ranch buildings survive in part, hard against the old alignment of the highway, and are shown on ranger-led walks rather than being open to visitors on their own.

Excavation at Pigeon's Ranch in 1987 uncovered a burial trench holding the remains of thirty-one Confederate soldiers, identified from uniform fragments and the surgical evidence of amputation. The remains were studied over the following years and reinterred at the Santa Fe National Cemetery in 1993, with a service attended by descendants of men who had served in both armies.

The pass itself is crossed today by Interstate 25 and by the railway, and very little of the terrain reads as a battlefield from the road. Markers stand at the eastern approach and near the ranch, and the Glorieta Battlefield is listed on the National Register of Historic Places.