Commander in Chief
Over the years, presidents have exercised more authority in their role as commander in chief than in any other facet of the job. It's without question the most important responsibility of the office. As commander in chief, the president has the ability to commit American troops to battle. It is the most difficult decision a president can make, and is always handled with great care and reflection.
The framers of the Constitution were careful not to vest too much military power in the presidency for fear of creating an abusive and unjust government, or even a military dictatorship. Therefore, the Constitution gives the Congress the authority to declare war, raise an army, and fund wars, while it gives the president the power to manage and execute military action. The framers did not want the president to have the ability to both declare and execute wars without Congressional involvement.
For the most part, nineteenth-century presidents adhered to the Constitution when it came to decisions of war, consulting Congress on military actions and committing troops only with formal declarations of war. Preceding both World War I and World War II, however, the Congress delegated by statute to the president increased authority to fight wars. The onset of the cold war with the Soviet Union resulted in even greater military authority for the president, as the Congress believed that he was best able to combat the growing menace of communism and the threat of nuclear war.
The Korean War was the first large-scale war for which the president did not seek prior Congressional approval. Harry Truman cited the commander-in-chief authority as well as a United Nations resolution authorizing the use of force as justification for sending troops into battle without a formal declaration of war. Ten years later, President Lyndon Johnson relied on this precedent to send troops to Vietnam — another undeclared war.
In August of 1964, the Congress passed the Tonkin Gulf Resolution, a joint resolution that authorized President Lyndon Johnson to use military force in Vietnam. The resolution resulted from the purported attack on the naval destroyer USS Maddox by two North Vietnamese gunboats. A Congressional investigation in 1968 revealed that the Johnson administration had mostly fabricated the incident as a pretext to war.
In response to the Vietnam War, the Congress passed the War Powers Act in 1973 over President Richard Nixon's veto. With this act, the Congress tried to reign in the president's ability to make war, setting out a specific set of conditions under which he could commit troops without prior Congressional authorization. Even though the Supreme Court has struck down parts of the act as unconstitutional, it has been somewhat successful in forcing presidents to seek Congressional approval before sending troops into harm's way. President George H. W. Bush received Congressional authorization to use military force in the first Gulf War, as did President George W. Bush prior to Operation Iraqi Freedom.
As part of his commander-in-chief function, the president is in charge of the armed forces — he is the first general and admiral. Presidents have approached the military commander function differently. Depending on their background, some have taken a more hands-on approach, while others have left all the decision-making up to their generals. In 1794, George Washington nearly took charge of the militia that put down the Whiskey Rebellion. During the Civil War, Abraham Lincoln was deeply involved in strategy, troop movements, and battle plans, and on occasion even gave direct orders to his field generals. President Wilson left the battlefield strategy to the military during World War I, as did President Franklin Roosevelt (for the most part) in World War II. Lyndon Johnson was famous for selecting specific bombing targets in Vietnam. In Operation Iraqi Freedom, President George W. Bush approved the overall military strategy, but did not involve himself in any tactical decisions.
Wherever the president goes, a military aide follows him carrying “the football” — a briefcase containing all the codes and documents necessary to order a nuclear launch. The president is the only person with the power to authorize a nuclear launch. President Kennedy created “the football” following the Cuban missile crisis.