In early 1862, Confederate Brigadier General Henry Hopkins Sibley persuaded Jefferson Davis to back an invasion up the Rio Grande from the Confederate Arizona Territory, with plans to seize the Colorado gold fields and then Pacific ports in Southern California. After occupying Santa Fe in March 1862, his Texans needed Fort Union, and the road there ran through Glorieta Pass in the Sangre de Cristo Mountains. This episode covers the Colorado volunteers under Colonel John P. Slough who marched about 400 miles from Denver in 14 days to block them.

On March 26 at Apache Canyon, Major John M. Chivington’s men climbed the canyon walls and drove back Major Charles Pyron’s Texas veterans. Both sides reinforced, and on March 28 William R. Scurry’s Confederates pushed Slough’s force back from Pigeon’s Ranch to Kozlowski’s Ranch. Meanwhile, Chivington’s detachment, guided by Lieutenant Colonel Manuel Chaves, found the Confederate supply train at Johnson’s Ranch and destroyed it. Without supplies, the Confederates retreated to Santa Fe and eventually San Antonio. The episode also covers the dispute over who deserved credit for the raid and the Gettysburg of the West label.

• Slough divided his army, sending Chivington with about 400 men on a wide loop through the mountains.
• Confederates seized high ground later called Sharpshooter’s Ridge and forced a Union retreat at Pigeon’s Ranch.
• At Johnson’s Ranch, Union troops burned 80 wagons, spiked cannons, and killed or scattered about 500 horses and mules.
• Indian affairs official James Collins said Chivington had to be persuaded for two hours before descending on the wagons.
• A mass grave with the remains of 30 Confederate soldiers was found at Pigeon’s Ranch in 1987, now within Pecos National Historical Park.