Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Brooks saw combat in both the Seminole and Mexican-American Wars. He participated in the battles of Battle of Palo Alto and the Battle of Resaca de la Palma in 1846. He saw considerable action in the Battle of Monterrey, and received a brevet to captain for "gallant and meritorious conduct." The following year, Brooks was at the Siege of Vera Cruz, the Battle of Cerro Gordo, the Skirmish of Ocalaca, the Battle of Contreras, and Battle of Churubusco. He was received a brevet promotion to major, August 20, 1847, for gallant and meritorious conduct at Contreras and Churubusco. He served on the staff of Gen. David E. Twiggs for the rest of the war. He was promoted to Captain, 3rd Infantry, November 10, 1851, then served on frontier duty in the New Mexico Territory until 1858, at times skirmishing with local Navajos. He then served at Fort Clark, Texas, until1861, when he returned to the East for garrison duty at Fort Hamilton, New York, where he was stationed when the Southern states seceded.