American Military History, Volume 1

In the three decades after 1815, the Army pushed westward ahead of the settlers, surveying, fortifying, and building roads. (Map 19) Stockades and forts built and garrisoned in Iowa, Nebraska, and Kansas became the footholds of settlement in the wild frontier; just outside the walls could be found gristmills, sawmills, and blacksmith shops, all of them erected by the troops. Fort Leavenworth, established in 1827 as the first permanent fort on the western bank of the Missouri River, was the main base for Army expeditions sent out along the Santa Fe and Oregon Trails.

An important Army explorer in the 1830s, Capt. Benjamin L. E. Bonneville of the 7th Infantry, took a four-year leave of absence and made valuable observations concerning the Pacific coast. These early expeditions were made by infantrymen using steamboats, wagons, and oxcarts. The expert horsemanship and tactical mobility of the Indians on the Great Plains also prompted the Army in 1832 to organize its first battalion of mounted rangers. The battalion was expanded the following year into a regiment of dragoons, essentially horse-mounted infantry, the first cavalry-type units to appear in the Regular Army since 1815.