Raised in Kentucky with little formal schooling, Zachary Taylor received a U.S. Army commission in 1808. He became a captain in 1810 and was promoted to major during the War of 1812 in recognition of his defense of Fort Harrison against attack by Shawnee chief Tecumseh. In 1832, he became a colonel and served in the Black Hawk War and in the campaigns against the Seminole Indians in Florida, winning the nickname of "Old Rough and Ready" for his informal attire and indifference to physical adversity.
Sent to the Southwest to command the U.S. Army at the Texas border, Taylor crossed the Rio Grande with the outbreak of the Mexican-American War in 1846. In May, Taylor defeated the Mexicans at the battles of Palo Alto and Resaca de la Palma, and in September he captured the city of Monterrey. In February 1847, he achieved his crowning military victory at the Battle of Buena Vista, where his force triumphed despite being outnumbered three to one. This victory firmly established Taylor as a popular hero, and in 1848, despite his lack of a clear political platform, he was nominated the Whig presidential candidate.
Elected in November, Taylor soon fell under the influence of William H. Seward, a powerful Whig senator, and in 1849 he supported the Wilmot Proviso, which would exclude slavery from all the territory acquired as a result of the Mexican War. His inflexible responses to Southern criticisms of this policy aggravated the nation's North-South conflict and revealed his political inexperience. Matters were at a stalemate when he died suddenly on July 9, 1850.