This report is designed to assist Congress as it considers how to proceed with the proposed nomination of General (Ret.) James Mattis to be Secretary of Defense. After exploring the history of the statutory restriction and its evolution over time (see " Preserving Civilian Control of the Military in the 1947 Act and Restricting the Position of Secretary of Defense "), it touches upon some of the broader questions that have recently been raised in the public debate on whether, and how, this proposed nomination might impact civilian-military relations and the principle of civilian control of the military. How to advance the nation's security while at the same time ensuring that instruments of force do not undermine the practice of American democracy has been a central question since the founding of the United States, if not before. The principle of civilian control of the military places ultimate authority over U.S. armed services in the hands of civilian leadership, with civilian responsibility and control of the military balanced between the executive and legislative branches of the government. In some ways, the relationship between the military and the civil society it serves can be thought of as a paradox: the military, by its very nature, has coercive power that could threaten civil society. Yet without a sufficiently strong and capable military, civil society becomes vulnerable to attack, and the former might not be able to defend the latter. The United States has balanced this tension through formulating and promulgating the principle of civilian control of the military. The fact that this principle has remained relatively unchallenged over the course of American history is, by most accounts, remarkable. This section briefly outlines the history of the principle of civilian control of the military, and how it influenced legislation over time. The designers of the Constitution were deeply skeptical of a standing military as, much like Oliver Cromwell demonstrated in 1653 when he used his army to disband Parliament, such a military instrument could also overthrow the government it professed to serve. Indeed, consternation regarding the British deployment of its military to the American colonies without the consent of local governing officials was among the key grievances listed in the Declaration of Independence and helped inform the Third Amendment of the Constitution. Applied to the context of a new, experimental, and democratic Republic, the Founding Fathers believed that subordination of the military to the authority of civil masters was critically important in order to prevent the emergence of a new form of tyranny or dictatorship. The principle was put to the test even before the American state was founded. During the Revolutionary War, particularly, upon the surrender of Cornwallis at Yorktown, the prestige of the American military was at its height, while regard for the Continental Congress—the civilian authority to which General George Washington reported—was dwindling. Had Washington, a popular figure at the time, been any less devoted to democratic principles, a New World variety of despotism might have been established. Indeed, there were ample opportunities for General Washington to install himself as a dictator—which would likely have had the end result of swapping one form of monarchical rule for another. As the war drew to a close, a group of his associates, cognizant of the impotence of the American Confederation, begged him to set himself up as the authoritarian head of a new government. Washington refused, arguably preventing the emergence of a military-authoritarian government in the process. Subsequent to the Revolutionary War, the fragility of the Confederation government was highlighted by the 1786 Shays rebellion, the first armed rebellion in the post-Revolutionary United States . The Shays Rebellion was a local uprising in Massachusetts in response to high taxes and difficult economic conditions. In September 1786, Captain Daniel Shays, along with other Massachusetts leaders, led several hundred armed men to close some local courts in order to prevent the execution of foreclosures and other debt processes. In January 1787, Shays led approximately 1,200 men in an attack on the federal arsenal at Springfield, MA. The local Massachusetts government put down the rebellion in February 1787. While the rebellion itself was small, and was quickly suppressed, for some it became a compelling argument for why the United States needed a stronger national-level government, including a standing army and militia. The challenge was how to do so while at the same time preventing the emergence of a national military that could threaten the new Republic . Accordingly, the Founding Fathers designed a system of civilian control of the military in a manner that conformed with its overall architecture of checks and balances. An elected President was designated the Commander-in-Chief of the nation's armed forces. This had the dual advantage of ensuring that an elected civilian leader presided over the nation's army while at the same time enhancing unity of command over the military. The President was also granted the ability to commission military officers, authority to appoint Secretaries to preside over military services, and the responsibility to regularly report to Congress on the state of the union. The desire to ensure that the military reflected, and was subordinate to, the will of the people also led to considerable congressional powers on matters concerning the armed services. Congress was granted the power to lay and collect taxes for the common defense. Congress was also given the sole power to declare war, the ability to raise and support armies, establish rules and regulations for the army, navy, and militias when in service of the United States. Finally, to hamper the establishment of a permanent, standing military, a provision was made specifying that no appropriation of money could be made for the army for a period longer than two years. This governance architecture was necessary, but not sufficient, to ensuring civilian control of the military. Here again, George Washington played a vital role in establishing the norms and culture that formed the foundation for American relationships between the military and the civilian leadership it served (also referred to as "civil-military" or "civilian-military" relations). For example, in putting down the 1794 Whiskey Rebellion in western Pennsylvania, President Washington ensured that his subordinates understood the importance of upholding civil rule of law while doing so. Despite disagreements—sometimes vehement—between military and civilian leaders throughout the nation's history, contemporary scholars of civil-military relations have noted that these norms, inculcated and promulgated by Washington and his successors, remain robust. Another reflection of American skepticism towards a standing army—and the desire to ensure that it remained under civilian control—was a general policy to keep the peacetime active duty army relatively small. Indeed, from the founding of the nation to the Cold War era, the bulk of force structure was maintained in the reserve component (especially the militia/National Guard), except in times of major conflicts. When major conflicts arose—such as the Civil War, World War I, and World War II—the comparatively small active component was expanded through the activation of militia and federal reserves, recruitment of additional volunteers for the active component, and the use of conscription. At the end of the conflict, active force levels were dramatically reduced. For example, in 1916, the end strength of the active duty military was approximately 179,000 personnel; over the course of World War I, this grew to nearly 2.9 million. After the war's conclusion, U.S. military end strength decreased to approximately 250,000. Similarly, in 1939, there were fewer than 350,000 active duty personnel in all branches of the U.S. armed forces. During World War II, this number grew enormously, reaching over 12 million servicemembers on active duty by 1945. While this approach to organizing for military campaigns generally suited the preferences of the American people and its leaders—and in particular, their overall skepticism towards a standing army—it came at the expense of preparedness. This resulted in the expenditure of more American blood and treasure during wartime than would have happened if there had been greater peacetime investment in the armed forces, an issue that was apparently not of great concern until World War II. For the first century and a half of the United States' history, the architecture designed at the Constitutional Convention, combined with the American military cultural norm of respecting civilian control of the military and the preference to disband the military after cessation of hostilities, served to largely circumscribe the armed forces and prevent them from becoming overly dominant within the U.S. government. After World War I, the concept of a single defense establishment was considered around Washington, but the military services opposed such proposals and blocked their serious consideration. Yet it was the experience of World War II—the surprise of Pearl Harbor, America's initial lack of preparedness, and a deficiently structured military organization to wage the campaign—that forced a serious reconsideration of the design of U.S. institutions associated with national security, and in particular, the military. The old way of doing business was no longer viewed as sufficient by most observers at the time. To that end, Congress began considering how to restructure its national security institutions as early as 1944, although it did not entertain serious recommendations and proposals until after the conclusion of the war. On December 6, 1945, President Truman submitted a letter to Congress arguing that the existing War and Navy Departments should be combined into a single Department of National Defense. Until that time, the Departments of War and Navy operated separately, each headed by a cabinet-level Secretary, with the effective execution of military operations relying on voluntary coordination between the departments. President Truman contended that such voluntary coordination was inadequate and argued for the integration of the military services into a single department, which would report to a new cabinet-level advisor on matters of national defense. The merits and risks of creating a new Department headed by a single individual were therefore vigorously debated by the military services, the executive branch, and Congress between 1944 and 1947. Although the United States has utilized a variation of Truman's proposed system of military governance for the past 60 years, there was, at the time, considerable pushback against his ideas. The proposal was controversial for at least three reasons.