The Battle of Glorieta Pass was dubbed the "Gettysburg of the West" by historians, it was the decisive blow by Union forces to stop the Confederate invasion of the West along the base of the Rocky Mountains.
The commanders of the New Mexico Campaign were the Confederate Brig. Gen. Henry H. Sibley and the Union Col. Edward Canby. Sibley had outmaneuvered Canby at the Battle of Valverde in February, driving Canby back to his fort, then advancing up along the Rio Grande Valley to seize Santa Fe on March 10. Sibley set up his division headquarters at the abandoned Union storehouse garrison at Albuquerque.
At the southern tip of the Sangre de Cristo Mountains, 20 miles southwest of Sante Fe in northern New Mexico, is La Glorieta Pass, through which runs the old Sante Fe Trail. Sometimes called Apache Canyon, the pass is several miles long, about a 1/4 mile wide at the middle, and tapers to narrow defiles at both ends. Ordered on March 25 to move against the Confederates force at Santa Fe, Maj. John M. Chivington and a raiding party of 418 Union soldiers arrived at Kozlowski's ranch, about 5 miles southeast of La Glorieta. From Confederate pickets captured that night, Chivington learned of the presence of 250-300 Texans under Maj. Charles L. Pyron bivoucked at Johnson's ranch at the far end of the pass.
Early in the morning of March 26, Chivington moved toward the Confederates. About 2:00 P.M., his men captured a 30-man Confederate advance, then fell on Pyron's main force 1.5 miles west of Pigeon's ranch, which lay 6 miles northeast of Johnson's ranch. With his advance guard taken by the Federals, Pyron was caught by surprise, but he quickly threw out a skirmish line, and his 2 6-lb. howitzers began firing shells at the Federals. The artillery fire sent the Federals into confusion until Chivington divided his troops, sending 3 companies to find cover in the rocks and deploying 2 companies in the cottonwood and pines along the mountain slopes on each side of the canyon; this placed the Confederates in a crossfire. The Texans held their ground briefly before Pyron withdrew about 1.5 miles to where the pass narrows. There, he was able to establish a stronger defense. As they pulled back, the Texans destroyed the bridge they had used to cross a 15-foot arroyo.
Again, Chivington sent his men to the slopes, but in increased numbers, to counter the Confederate skirmishers Pyron had ordered to the brush. The Federals flanked the Texans and poured another severe enfilading fire on them for an hour before Pyron's men broke. As the Confederates retreated with their guns, the Union cavalry charged, jumping their horses across the arroyo and landing in the midst of the Confederate rear guard. Gathering 60 or 70 prisoners, Chivington withdrew to Kozlowski's ranch, having lost 19 killed, 5 wounded, and 3 missing. The Confederates claimed casualties of 16 dead and 30-40 wounded in the day's fighting.
As his men reorganized at Johnson's ranch, Pyron sent for reinforcements from Lt. Col. William R, Scurry at Galisteo, 15 miles south of La Glorieta. Scurry arrived with the 4th Texas on the morning of March 27, bringing the Confedeate force to 1,100 men. They waited 24 hours at Johnson's ranch, expecting Chivington to renew the attack. When the Federals failed to act, Scurry decided to take the offensive.
On the morning of March 28, he moved down the canyon toward Pigeon's ranch, leaving behind his 73-wagon supply train and, to guard the camp, a detachment of 200 men, most of them wounded, drivers, or cooks.
About 2:00 A.M. the same morning, Col. John P. Slough had reached Kozlowski's ranch with reinforcements. Chivington briefed him on the Confederate position and Slough decided to launch an attack against Johnson's ranch, moving toward Pigeon's ranch about 8:30 A.M. He ordered Chivington to take his men and circle around La Glorieta Pass to attack the Texans from the west, intending to catch the Confederates between the 2 Union forces. Slough moved toward La Glorieta with about 900 men, arriving a mile west of Pigeon's ranch.
By that time, Scurry had advanced down the canyon, and his scouts saw the Union column approaching. Immediately, he ordered his cavalry to the rear, where they dismounted and formed a battle line. Slough discovered the Confederate line at 800 yards, and the battle began between 10:30-11:00 A.M. Slough's 8 field guns battered the Texans artillery into uselessness, but the Confederates were able to keep a company of the 1st Colorado from moving around their flank. Slough yielded ground. Five times the Confederates charged, losing all of their field officers killed or wounded. They finally broke under 6 volleys from Slough's artillery, followed by a bayonet charge, but retook their lines when the Union troopers were repelled by a deadly barrage of gunfire from the Texan sharpshooters. The fighting ended about 5:00 P.M., when Slough retreated to Pigeon's ranch. Scurry also withdrew, leaving his wounded on the field.
Initially, Scurry believed he had repeated the Confederate victory at Valverde, where a month earlier, Brig. Gen. Henry Hopkins Sibley's troops had defeated a Union force under Col. E.R.S. Canby. Later, he learned that Chivington had reached Johnson's ranch, but burned the Confederate supply wagons, bayoneted 500-600 mules and horses, and captured 17 prisoners. Chivington had destroyed nearly all of the Confederates' supplies, forcing the Confederates to withdraw to Texas, thus giving the victory to the Union. So complete was their devastation that during a truce in the early evening, the Texans even had to borrow Union shovels to bury their dead. Scurry was forced to retreat to Santa Fe, the first step on the long road back to San Antonio, Texas.
The fighting then ended as Slough retired first to Pigeon’s Ranch and then to Kozlowski’s Ranch. Scurry soon left the field also, thinking he had won the battle. Chivington’s men, however, had destroyed all Scurry's supplies and animals at Johnson's Ranch, forcing him to retreat to Santa Fe, the first step on the long road back to San Antonio, Texas. The Federals had won and, thereby, stopped Confederate incursions into the Southwest. Glorieta Pass was the turning point of the war in the New Mexico Territory. Canby was promoted to brigadier general 3 days after his victory.
Chivington had delivered a severe blow to the Confederate incursion into the Southwest, one from which the Confederates never recovered. The Confederate defeat at La Glorieta Pass marked the military turning point of the war in New Mexico territory.
Chivington, later in the war, commanded a force on November 29-39, 1864, in Sand Creek, Colorado. This engagement was known as "Chivington's Massacre."