He is primarily remembered for his defeat at the Battle of Pine Creek during the Spokane-Coeur d'Alene-Paloos War.

During the Mexican-American War, he participated in the Siege of Vera Cruz, and fought in the Battles of Cerro Gordo, San Antonio Garita, Buena Vista, and Chapultepec.

[4] In 1854 he was sent by the War Department to Utah to investigate the recent massacre of John W. Gunnison and his survey party.

[5] Late in 1854, President Franklin Pierce offered Steptoe the governorship of the Utah Territory to replace Brigham Young.

[1] Steptoe was sent on sick leave after the battle, during which he was promoted to lieutenant colonel, and resigned due to ill health in November 1861.