José Guadalupe Gallegos was a native New Mexican military leader, county sheriff, rancher and politician. In 1854 he served as brigadier general in the volunteer Mounted Militia of New Mexico (Territory) formed for the purpose of protecting communities against Native American attacks. Prior to the Battle of Glorieta Pass, he was a Union field and staff Colonel in the Civil War, serving as commander of the 3rd New Mexico Volunteer Infantry and as commander of the Hatch's Ranch military post. He represented San Miguel County in four of the six Assemblies of the Territorial Legislature between 1855-1861 and served as House Speaker and as Council President. José was one of the founding members of the Historical Society of New Mexico and was a founding associate in the incorporation of the Montezuma Copper Mining Company of Santa Fé, New Mexico the New Mexican Railway Company and the New Mexico Wool Manufacturing Company.

Hispanics in the American Civil War fought on both the Union and Confederate sides of the conflict. Not all the Hispanics who fought in the American Civil War were "Hispanic Americans" — in other words citizens of the United States. Many of them were Spanish subjects or nationals from countries in the Caribbean, Central and South America. Some were born in what later became a U.S. territory and therefore did not have the right to U.S. citizenship. It is estimated that approximately 3,500 Hispanics, mostly Mexican-Americans, Puerto Ricans and Cubans living in the United States joined the war: 2,500 for the Confederacy and 1,000 for the Union. This number increased to 10,000 by the end of the war.