The Third U.S. Infantry built Fort Craig in 1852 after the Mexican-American War to replace ill-sited, poorly constructed, and short-lived Fort Conrad a few miles north. Its location on a low bluff overlooking the Rio Grande protected it from flooding and insects and provided ample horse forage because it stood above the river. Constructed of adobe and stone, it was named for Captain L.S. Craig, a popular young Mexican-American War officer killed by deserters while surveying the new international boundary. From 1854 to 1884, Fort Craig protected settlements and travelers in the Rio Grande Valley from raids by Apache and Navajo Indians, guarded the north-south El Camino Real along the Rio Grande, and helped open agricultural, mineral, and grazing lands to economic development. A succession of post commanders mobilized and deployed regular army and civilian militia forces across a wide operational range from the southern end of the Jornada del Muerto to north of Albuquerque, west to the headwaters of the Gila River, and east to the Pecos River, gradually eroding the ability of Indians to defend their homelands against encroachment. During the Civil War, Fort Craig also played a strategic role by sending Union troops to fight Texas Confederates in the bloody battle of Valverde across the river, dimming Southern aspirations for military conquest in the West.