Seal of the U.S. Army
Courtesy U.S. Army

The U.S. Army is a main branch of the U.S. military. With over one million Americans serving in the Army, Army National Guard and Army Reserves, and a 2007 budget of more than $110 billion, it's one of the largest military organizations in the world.

The Army's primary purpose is to protect the United States and its interests. This is accomplished by fighting in armed conflicts when the need arises, participating in peacekeeping and security duties and maintaining a state of readiness for war. While the Army does have units that utilize aircraft and watercraft, its main responsibility is land-based combat.

Two main branches make up the Army: the operational branch and the institutional branch. The operational branch conducts the more visible aspects of the Army's job, which involves combat and peacekeeping. The institutional branch of the Army is responsible for training and maintaining soldiers and equipment so the operational branch can do its job effectively.

Within the operational branch, there are two divisions:

  • The regular army, also known as the active Army. Its units may be deployed around the world at any given moment. Roughly 60 percent of the Army's troops are in the regular Army.

  • Reserve components, which comprises the U.S. Army Reserve and the Army National Guard. Soldiers (the official term for anyone in the Army) in the reserve typically train one weekend per month, with a two-week training period occurring once each year. These part-time soldiers may be called up to full-time whenever the Army needs them. Some are divided into units made wholly from reserves, while other reserve soldiers fill out the ranks of regular Army units.

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Today's Army is an all-volunteer force. While this generally results in high-quality soldiers (because they all actually want to be in the Army), it can be difficult to get enough recruits to keep the Army fully manned. In 2005, the Army fell short of recruiting goals, but met its recruiting benchmarks in 2006. The United States has used conscription (mandatory military service, also known as "the draft") several times in the past. Drafts were used in the War of 1812 and by both Union and Confederate forces during the American Civil War. The draft was instituted again during both World Wars, and was used during the Cold War in the late 1940s and early 1950s (the only time a peacetime draft was used). The last draft occured in 1973, during the war in Vietnam. Since 1980, the United States has used the Selective Service System to register all males when they reach age 18. This system is designed to make it easier for the government to find and enlist soldiers if a draft is reinstated. However, no one has been prosecuted for failing to register since the mid-1980s.

To supplement the active Army with reserves, Congress generally needs to have declared an emergency or a war, which gives the President the authority to call up those troops held in the reserves for the length of the situation plus six months. The President can also call up reserves without Congressional authority for a limited amount of time. In addition, the President can activate members of the National Guard. The length of time a National Guardsman can serve in active duty overseas has increased from six months to 24 months because of personnel shortages caused by the war in Iraq.

Next, we'll look at the Army's hierarchy.