Institutional practices evolve to fill gaps in all constitutional blueprints. One of the underappreciated features of the initial constitutional settlement of war powers was the accountability of the executive through the process of budgetary authorization and the corresponding need for Congress to answer to the citizenry for the tax implications of military expenditures. This political accountability is more complex than often described, consisting not merely of the division of the Declare War and Commander-in-Chief Clauses of Article I and Article II, but also of the temporal limitation of the budgetary power for the army and a variety of practical and political obstacles to prevent the president from going it alone in warfare. The thesis of this Essay is that critical features of the ensuing constitutional equilibrium, which largely controlled the war power even in the absence of formally declared hostilities, have come undone as a result of the declining social and economic costs of modern forms of warfare, the development of the permanent and socially insular standing army, and the rise of its associated military-industrial complex as an independent institutional actor. The combination of an enormous, permanent military budget and the elimination of conscription has eroded the effectiveness of the institutional division of authority over war that emerged in the earliest days of the republic. This broader phenomenon of constitutional disequilibrium, in which constitutional doctrines and settlements prove dependent on the existing state of technology and institutional arrangements, in turn highlights the difficulty of managing today’s warfare in a fashion that avoids executive unilateralism.