Absent from war-powers scholarship is an account of when war and military powers separate and when they overlap. Making arguments sounding in text, structure, and history, this Article supplies such a theory. Numerous English statutes and practices help identify the meaning of the Constitution’s war and military powers. Additional insights come from the Revolutionary War and the half-dozen or so wars fought in the three decades after 1789. In those early years, Congress micromanaged military and wartime operations. Presidents (and their advisors) acquiesced to these congressional assertions of power, expressing rather narrow understandings of presidential power over war and military matters. Using early history as a guide, this Article argues that the Constitution grants Congress complete control over all war and military matters. Some authorities, such as the powers to declare war and establish a system of military justice, rest exclusively with Congress. Military authorities not granted exclusively to Congress vest concurrently with the President and Congress, meaning that either can exercise such powers. In this area of overlap, where congressional statutes conflict with executive orders, the former always trump the latter. Tempering Congress’s ability to micromanage military operations are significant institutional and constitutional constraints that typically make it impossible for Congress to move military assets on a far-off battlefield. In sum, the Constitution creates a powerful Commander in Chief who may direct military operations in a host of ways but who nonetheless lacks any exclusive military powers and is thus subject to congressional direction in all war and military matters.