Our Story

The Department of Defense provides the military forces needed to deter war and ensure our nation’s security.

The foundational strength of the Department of Defense is the men and women who volunteer to serve our country and protect our freedoms. Watch the video and then dive into the site to learn more.

At a Glance


Budget pie graph


  • National Defense Budget
  • 3.1% of Gross Domestic Product


people icon


  • 2.15 Million Service Members
  • 732,079 Civilians
  • America’s Largest Employer


world Icon


  • All 7 Continents
  • Approximately 4,800 Defense Sites

Our Forces

The men and women serving in our armed forces have helped forge a sense of identity and unity among Americans, particularly during times of strife.

Learn More

Combatant Commands

The 11 unified combatant commands provide effective command and control of U.S. military forces around the world, in peace and war.

Learn More


The Pentagon, located in Arlington, Virginia, is one of the world’s largest office buildings. It has 17.5 miles of hallways, three times the floor space of the Empire State Building, and houses about 26,000 employees.

Pentagon Tours




















A painting shows men in colonial garb gathered outside, with ship masts in the background.

As the American Revolution begins, the Second Continental Congress establishes the Army, Navy and Marine Corps.

Badge of Merit, the Purple Heart is America’s oldest military award.

Gen. George Washington establishes the Badge of Military Merit, America’s first formal medal for rewarding individual acts of gallantry.

A painting shows a man in colonial garb standing and gesticulating in a room with seated men and an early U.S. flag adorning a wall.

Congress authorizes the War Department, a precursor of what is now the Department of Defense.

Beams of light emanate out on a dark gray sky from a white lighthouse.

Congress establishes the Coast Guard, now part of the Department of Homeland Security in peacetime.

War Department Building

On August 24, as the War of 1812 against the British continues, the War Department building is burned. All books and records are saved, having been removed earlier in the week.

Medal of Honor recipient Army Pvt. Jacob Parrott.

Congress authorizes the establishment of the Medal of Honor. The first recipient is Private Jacob Parrott. Since its establishment, more than 3,500 medals have been presented.

Construction debris sits in front of the beginnings of a building

Congress authorizes construction of the Pentagon, and ground is broken September 11. The land belonged to Confederate Gen. Robert E. Lee before it was confiscated during the Civil War.

Cars sit parked in rows in a lot outside the Pentagon.

While the Pentagon’s construction is not complete, the first employees begin working inside the building.

People walk on a walkway in the Pentagon courtyard.

After 16 months of construction, the Pentagon officially opens for business.

Three men stand around a desk where another man is seated.

The single biggest military reorganization of the era replaces the War Department with the National Military Establishment and splits the Air Force from the Army to create a separate service.

President Harry S. Truman signs a document at his desk in the Oval Office, as men stand around him and watch.

Congress renames the National Military Establishment the Department of Defense.

Army military police officers use weapons to block a crowd demonstrating against the Vietnam War outside the Pentagon, Va., Oct. 21, 1967.

In October, more than 25,000 anti-Vietnam War demonstrators march from the Lincoln Memorial to the Pentagon to protest American involvement in the war.

An aerial view of the Pentagon. DoD photo

The Pentagon is added to the National Register of Historic Places.

A soldier's white-gloved hands hold up a National Historic Landmark plaque for the Pentagon.

The Pentagon is added to the National Historic Landmarks list.

Construction personnel on ladders and scaffolding work with steel rods against a wood facade.

Pentagon renovations begin, one wedge at a time. Building systems are modernized, and a new LEED-certified Metro entrance, delivery facility and fitness center are created.

A destroyed section of a Pentagon facade is sandwiched by intact sections, with fire vehicles parked in front.

In the September 11 terrorist attack on the Pentagon, 59 people aboard American Airlines Flight 77 and 125 people inside the building perish.

Lights illuminate memorial benches at the National 9/11 Pentagon Memorial.

The Defense Department honors those killed in the 9/11 attack with the opening of the National 9/11 Pentagon Memorial.

Two helicopters fly over the Pentagon as military musicians march on the parade field.

Pentagon renovations are complete. One of the world’s largest office buildings, the Pentagon has three times the floor space of the Empire State Building. To find out more and book a tour click here.