This dissertation examines early-nineteenth-century Native American incarceration in the upper Mississippi Valley between 1803 and 1849. Drawing upon military and government documents, court records, treaties, and legal questions under the Trade and intercourse Acts--as well as upon memoirs, travel narratives and newspaper articles--it explores how and why United States officials routinely incarcerated Native American men living on those lands which now comprise the states of Missouri, Illinois, Iowa, Wisconsin and Minnesota. It details the experiences of Indian prisoners held in military fort guardhouses and small town jails as they endured and negotiated the terms of their incarcerations, with the assistance of family and tribal communities on the "outside." During the early nineteenth century, before the establishment of large state penitentiaries in the upper Mississippi Valley--Native American men in the region faced two forms of incarceration: they were either held in municipal and county jails as "murder" suspects for civil trial, or they were detained in military fort guardhouses as hostages for the future "good conduct" of their respective villages, bands and/or tribes. I argue that in both cases, imprisonment was intended to be both punitive and reformative and was inseparable from federal geopolitical maneuverings that enabled U.S. conquest of the region--in the name of "peace." Whether Native men were held in municipal jails for civil trials, or in military guardhouses as hostages, their incarceration was directly, or indirectly, tied to the social control of larger Native collectivities and worked to bolster U.S. military, political, legal and economic hegemony in the region. As such, these carceral practices constituted a glaring contradiction of U.S. officials' often repeated dictum that as "fair" and "benevolent" arbiters of "Indian affairs," they would never punish the "innocent" for the behaviors of the "guilty." Moreover, the legal and geopolitical status of imprisoned Indian men during this period was marked nebulous, fluid, and expedient, for it was contingent upon the nonspecific legalese of various treaties and federal laws as well as upon U.S. officials' ever-changing, on-the-ground geopolitical calculations. This dissertation intervenes in histories of nineteenth-century U.S. penology and of Anglo-American conquest in the upper Mississippi Valley which essentially ignore the significance of Indian incarceration and the experiences of Native prisoners. It also intercedes in the sizeable body of work concerning the Sauk leader Black Hawk and his "war" against the United States in the summer of 1832. Arguably, Black Hawk became--and has remained--the most prominent of Indian prisoners in the region. However, accounts of Black Hawk have failed to consider his incarceration within the larger carceral landscape to which Indian men were routinely subjected; moreover, those accounts have neglected the significance of Indian incarceration (beyond Black Hawk's) to military officials' prosecution of the Black Hawk war.