In this article, I argue that leaders of the U.S. Department of War and U.S. Army developed the organizational form and management practices of the modern corporation, decades before the advent of the railroads. Following Mark R. Wilson’s call to “bring the military in” to organizational analysis, I show how leaders of the U.S. military developed modern management practices and organizational structures as a way of maintaining control over officers, soldiers, and workers over long distances, as they provided the organized violence necessary for domestic imperialist expansion. By the time that elite merchants and real estate interests in the Atlantic port cities of the U.S. became interested in building railroads, in the late 1820s and 1830s, the U.S. Army already evidenced the key characteristics of modern business enterprise as defined by Alfred Chandler: a multi-unit organization coordinated by a hierarchy of professional, salaried, career-oriented middle and top managers. All the characteristic coordination mechanisms of the corporation: staff and line hierarchies, divisional and departmental structure, and bureaucratic systems of information gathering, surveillance, and control, were developed by the state in the course of building a continental empire.