Prior to the battle, Union forces performed a forced march from
Denver, over Raton Pass, to Fort Union and then to Glorieta Pass, covering the distance of in 14 days. Combat commenced shortly after their arrival at the battlefield, leaving them little time to recuperate.
Apache Canyon Pyron's force of 300 camped at Apache Canyon, at one end of Glorieta Pass, leaving a picket post of 50 men at the summit of the pass. Chivington led 418 soldiers to the pass, and on the morning of March 26, moved out to attack. After noon, Chivington's men captured the picket post and found the main force behind them. Chivington advanced on them, but their
artillery fire threw him back. He regrouped, split his force to the two sides of the pass, caught the Confederates in a crossfire, and soon forced them to retire. Pyron retired about to a narrow section of the pass and formed a defensive line before Chivington's men appeared. The Union forces flanked Pyron's men again and punished them with
enfilade fire. Pyron ordered another retreat, but the withdrawal of the artillery caused the Confederates to become disorganized and start fighting in separate clusters of men. Chivington ordered a mounted Colorado company to make a frontal charge against the artillery; this succeeded in capturing several Confederates and scattering the rest. Not knowing if Confederate reinforcements were nearby, Chivington then retired and went into camp at
Kozlowski's Ranch to await Slough with the main body. His small victory was a morale boost for Slough's army. No fighting occurred the next day, as reinforcements arrived for both sides. Scurry's troops arrived at 3:00 am on March 27, swelling the Confederate force to about 1,100 men and five cannons; as senior officer present, he took command of the entire Confederate force. Thinking that Slough would attack again and expecting Green to arrive in the Union rear at any time, Scurry chose to remain in place for the day, digging rifle pits. Slough arrived early in the morning of March 28 with about 900 more men, bringing the Union strength to 1,300.
Glorieta Pass Both Scurry and Slough decided to attack on March 28 and set out early to do so. Expecting the Confederates to remain in Apache Canyon, Slough sent Chivington with two infantry battalions, under Lewis and Wynkoop, out in a circling movement with orders to go hide out at Glorieta Pass and hit the Texans in the flank once Slough's main force had engaged their front. Chivington did as ordered, and his men waited above the pass for Slough and the enemy to arrive. Instead of remaining at Apache Canyon as Slough had expected, though, Scurry advanced down the canyon more rapidly than Slough had anticipated. Scurry believed the Union force was retreating to Fort Union. He intended to attack them until Green could arrive. One cannon and a small guard were left at Johnson's Ranch, while the rest of the Confederate force—more than 1000 men—marched eastwards along the Santa Fe Trail. When Slough found the Texans so far forward, he launched an attack, hitting them about 11:00 am, some from Pigeon's Ranch. A provisional battalion of four companies from the 1st Colorado, supported by both batteries, was commanded by Lt. Col.
Samuel F. Tappan, who deployed his men across the trail. The Confederates dismounted and formed a line across the canyon, but the terrain caused some companies to become intermingled. Tappan was initially successful and held his ground for a half-hour, but the Confederates' numerical superiority enabled them to outflank Tappan's line by noon. The Union troops were thrown back in confusion, but managed to take up position around the adobe ranch buildings. Slough reformed his men several hundred yards closer to
Pigeon's Ranch, with the four companies under Tappan and an artillery battery on a hill to the left, the other battery supported by two companies in the center across the road, and the remaining two companies on the ridge to the right. Scurry then launched a three-pronged attack. Pyron and Raguet were ordered to attack the Union right and Shropshire the Union left, with the remainder led by Scurry against the Union center, and the artillery firing in support. The attack on the Union left was beaten back, with Shropshire killed. The attack on the center stalled, while the artillery was forced to withdraw after one cannon was disabled and a limber destroyed. The attack itself then stalled, with the Confederates fighting by squads "with a desperation unequaled by any engagement of the war." At around 3:00 pm, the Confederates outflanked the Union right, but Raguet was mortally wounded. From the ridge (thereafter known as "Sharpshooters Ridge"), Confederate riflemen started picking off the artillerymen and infantry below them. Scurry again pressed the Union center, and the Union position became untenable. Slough reluctantly ordered a retreat, and Tappan formed the companies on the left into a rear guard. Slough reformed his line a half-mile east of Pigeon's Ranch, where skirmishing continued until dusk. The Union men finally retreated to Kozlowski's Ranch, leaving the Confederates in possession of the battlefield. They then looted and burned 80 supply wagons and
spiked the cannon, either killing or driving off about 500 horses and mules before returning with their prisoners to Kozlowski's Ranch. With no supplies to sustain his advance, Scurry had to retreat to Santa Fe, the first step on the long road back to
San Antonio, Texas. Thanks to Chaves' assistance, the Union had turned a defeat into victory and stopped further Confederate advances in the Southwest. Glorieta Pass was the turning point of the war in the New Mexico Territory. Parts of the
Glorieta Pass Battlefield are preserved in
Pecos National Historical Park and are the site of an annual NPS Civil War Encampment event commemorating the battle. ==Controversy==