For most of its first 170 years, the United States fielded a divided armed force. The Department of War oversaw the Army while the Department of the Navy managed the Navy and Marine Corps. Each department received its own budget from Congress and reported directly to the President. The vast scope of World War II and the increasing importance of joint effort by land, sea, and air forces highlighted the need for organizational reform. After considerable debate, Congress began the process of consolidation by passing the National Security Act of 1947, which President Harry Truman signed into law on 26 July. The act established the Air Force as a separate military service and unified all four branches of the military under a single executive authority, the Secretary of Defense. The Secretary, his immediate staff, and the three military departments (Army, Navy, and Air Force) constituted the National Military Establishment. The military departments initially retained considerable autonomy, and the first Secretary, James V. Forrestal, saw his small office primarily performing a role in coordinating and integrating their efforts.
In 1949 Congress amended the National Security Act to create the Department of Defense and shift much of the power of the military departments to it. The Secretary also took on broader powers to directly manage the armed forces rather than merely coordinate their activities. Subsequent legislation and reorganizations have further centralized control of the military services under the Secretary and the Department of Defense. The chain of command now runs directly from the President through the Secretary to the secretaries of the military departments for matters related to the provision of forces and to the commanders of the unified combatant commands for operational matters. The Joint Chiefs of Staff—consisting of a chairman, vice chairman, and the heads of the four services—provide military advice to the President and Secretary.
The American Revolution began on 19 April 1775 when colonial militiamen and British regulars clashed at Lexington. Militia units from other states rushed to Boston and surrounded the British in the city. On 14 June the Continental Congress adopted these militia elements in the field as a national army and authorized enlistment of soldiers into a Continental Army. The next day George Washington became its commander. When the war ended with British recognition of American independence in 1783, Congress decided that militia forces would remain the mainstay of American military power on the ground, but it also kept a small regular army in existence to protect the frontier and serve as the backbone for forces raised in wartime. The U.S. Army expanded exponentially with volunteers and draftees to fight the War of 1812, the Mexican War, the Civil War, the Spanish-American War, and both World Wars. It was only in the aftermath of World War II that the United States maintained a large peacetime Army to protect its global interests. From Bunker Hill in the Revolution through the streets of Baghdad in Iraq, the soldiers of the U.S. Army have served as the primary component of American land power and bravely defended the nation and its constitution.
The American colonies were in no position at the outbreak of the Revolution to challenge the Royal Navy’s command of the sea, but America did have a strong seafaring tradition. On 13 October 1775 the Continental Congress authorized a small Navy, primarily to attack British commercial shipping and disrupt supply lines to the British Army. The Continental Navy achieved some success, but it would take a French battle fleet to ensure victory at Yorktown in 1781. The new United States disbanded its Navy soon after, but in March 1794 Congress authorized construction of six frigates to deal with a threat to seagoing commerce from the Barbary states in North Africa. In 1798 Congress established the Department of the Navy to oversee naval matters. The U.S. Navy established its reputation during the War of 1812 by winning stunning ship-to-ship victories on the high seas and fleet battles on the Great Lakes over the vaunted Royal Navy. During the Civil War the U.S. Navy played a vital role in blockading the Confederacy and supporting the Union Army. Fleet battles in Cuba and the Philippines in 1898 determined the course of the Spanish-American War. In World War I, the Navy’s primary task was protecting American commerce and troop movements from German submarines. It would reprise that role in the Atlantic in World War II, but also fight numerous large-scale fleet actions with the Japanese in the Pacific and conduct dozens of amphibious assaults with soldiers and Marines on both sides of the globe. Since then the U.S. has remained the premier naval power and employed that capability to win the nation’s wars, advance diplomacy, and conduct humanitarian operations around the world.
The Continental Congress decreed on 10 November 1775 that “two Battalions of Marines be raised” for service with the Navy. That force fought at sea, made amphibious landings, and served with the Army; all roles that would become the hallmark of the Marines. They disappeared at the end of the Revolutionary War, but the Marine Corps was resurrected along with the Navy in 1794. The Corps remained small (under 10,000 men) for its first 140 years, but played a role in all the nation’s wars up to that point. During World War I the Corps grew to 75,000 and added its first significant aviation forces. In June 1918 4th Marine Brigade helped stop a German offensive at Belleau Wood in France and firmly established the reputation of the Corps in the hearts of the American public. Over the next two decades Marines honed their capability for amphibious operations—a mission that played a vital role in American victory during World War II, when half a million Marines helped spearhead the campaign in the Pacific. The Corps’ air-ground team also fought with distinction in Korea, Vietnam, Iraq and every significant American military operation up through the current conflict in Afghanistan.
Orville and Wilbur Wright achieved the first powered flight of an airplane on 17 December 1903. The Army acquired its first plane, from the Wrights, on 2 August 1909 and formed its first operational unit—the 1stAero Squadron—in December 1913. The Army Air Service came into being on 24 May 1918 and saw action in World War I. On 20 June 1941 the aviation component became the Army Air Forces (AAF), a co-equal element with the Army Ground Forces. Over the course of World War II, the AAF grew to 80,000 planes and 2.4 million personnel. The largest aviation force ever assembled, it supported ground forces and attacked the industrial capacity of Germany and Japan. In August 1945 two B-29 bombers dropped atomic bombs on Hiroshima and Nagasaki to bring the conflict to an end. On 18 September 1947 the Air Force came into being as a separate service. It would play a major role in the Cold War, with its cargo planes ferrying fuel and food in the Berlin Airlift, its new jet fighters battling Communist aircraft over Korea and interdicting supply lines in Vietnam, and its B-52 bombers and intercontinental ballistic missiles deterring a nuclear conflict. The role of air power reached a zenith in Operation Desert Storm in 1991 as it paved the way for the lightning victory on the ground and the liberation of Kuwait.
**History courtesy of DoD Deputy Chief Historian for the Office of the Secretary of Defense.