U.S. Army General. He is remembered for his significant contributions in the Mexican American War, especially the conquest of California. Born into a wealthy family, he attended local public schools and Columbia University in New York City, New York. In 1812 he left school to join the New York militia, serving as a 1st lieutenant in the War of 1812. Remaining in the US Army, he was assigned to the western frontier under command of Gen. Henry Atkinson where, in 1819, he was a member of the expedition to explore the Yellowstone River in present-day Montana and Wyoming, but it never went any farther than present-day Nebraska. In 1825 he was on the expedition that reached the mouth of the Yellowstone River. During his travels, he kept extensive journals, including his interactions with Native Americans. In 1826 he was appointed as the first commander of the new Jefferson Barracks along the Mississippi River in Missouri, south of St. Louis. In 1833 he was promoted to the rank of lieutenant colonel of the newly organized 1st Dragoon Regiment where he was the 2nd in command. The US Cavalry eventually grew out of this regiment, which was re-designated the 1st United States Cavalry in 1861, earning Kearny his nickname as the "father of the United States Cavalry". The regiment was stationed at Fort Leavenworth in present-day Kansas, and in 1836 he was promoted to the rank of colonel in command of the regiment in 1836. Additionally, he became commander of the US Army's 3rd Military Department, charged with protecting the frontier and preserving peace among the tribes of Native Americans on the Great Plains. By the early 1840s, when immigrants began migrating west along the Oregon Trail, he often ordered his men to escort the travelers across the plains to avoid attack by the Native Americans. The practice of the military's escorting settlers' wagon trains would become official government policy in succeeding decades. To protect the travelers, Kearny established a new post along Table Creek near present-day Nebraska City, Nebraska, named Fort Kearny. However, the Army realized the site was not well-chosen, and the post was moved to the present location on the Platte River in central Nebraska. In June 1846, at the outset of the Mexican American War, he was promoted to the rank of brigadier general and took a force of about 2,500 men to Santa Fe, New Mexico where he easily took control of New Mexico without a fight. He established a joint military and civil government there and after dividing his forces, he set out for California with 300 men and in December 1846 he encountered a Mexican force of about 150 Californio Lancers who surrounded them at the Battle of San Pasqual. With the assistance of US Marines and US Navy bluejacket sailors from San Diego, California, they succeeded in driving out the Mexican forces in January 1847 and took control of Los Angeles, California and the Treaty of Cahuenga terminated the fighting. He then assumed command of California as the ranking US Army officer despite the fact that California was brought under US control by Commodore Robert F. Stockton's Pacific Squadron's forces. Stockton and Kearny had the same equivalent rank (one star) and the War Department had not worked out a protocol for who would be in charge. Stockton seized on the treaty of capitulation and appointed John C. Frémont military governor of California. In April 1847 Kearny became the military governor of California until August 1847, when he traveled to Washington DC to a hero's welcome. He was then appointed governor of Veracruz, and later of Mexico City, Mexico. In September 1848 he received a brevet promotion to the rank of major general. The following month he contracted yellow fever and returned to St. Louis, Missouri where he died at the age of 54. The towns of Kearny, Arizona and Kearny, Nebraska are named in his honor. He was the uncle of American Civil War Union General Philip Kearny.