During the U.S.-Mexico War (1846-48), U.S. Army Colonel Alexander William Doniphan led a military expedition into the west. Doniphan, born in Kentucky in 1808, served as a lawyer, legislator and militia commander in Missouri. In May 1846, he recruited volunteer troops, which organized at Ft. Leavenworth (Kansas) to become the 1st regiment of Missouri mounted volunteers. Doniphan served as colonel of the regiment, which formed part of the army of the west commanded by Col. Stephen W. Kearney. The army departed Kansas. And after an 850-mile march, entered and occupied the provincial capital of Santa Fe without resistance. While there, Kearney and Doniphan became the first men to establish U.S. governance over a conquered territory, with Doniphan and citizen-soldiers drafting a territorial constitution. On December 1, the regiment left Santa Fe, marching south to capture El Paso del Norte (current day Ciudad Juarez). They defeated a larger Mexican force at Brazito before negotiating the peaceful surrender of the town. In February 1847, the troops left for the city of Chihuahua. They fought Mexican forces at the battle of the Sacramento and took formal possession of the capital city on March 1. The regiment later marched to Saltillo and returned home by way Matamoros and by boat across the Gulf of Mexico and up the Mississippi River. The one year, 5,000-mile expedition was crucial in securing victory over Mexico and led to the annexation of more than 1,000,000 square miles of what is now much of the western United States. Alexander Doniphan died in 1887, but the legacy of his expedition continues to impact El Paso, Texas and the United States. (2008)