Theophilus F. Rodenbough served as an officer with the Second Dragoons (still in operation today as the Second Armored Cavalry). Supplementing his account with personal recollections of other officers, he relates the history of the unit, beginning with operations in the Everglades against the Seminoles. He then follows Zachary Taylor and Winfield Scott during the Mexican War, recounting engagements at Buena Vista, Cerro Gordo, and Molino del Rey, as well as the siege of Mexico City.

Returning from expeditions to California and Utah, Rodenbough and his fellow officers next plunged into the Civil War, with the unit redesignated as the second Cavalry. They fought at Bull Run, Brandy Station, Gettysburg, Yellow Tavern, Trevilian Station, Winchester, and Cedar Creek. In the post-Civil War period on the western frontier, the Second Cavalry accompanied expeditions against the Sioux, Piegan, and Arapaho Indians, suffering its most grievous losses in the Fetterman Massacre of 1866.