History of the
U.S. Military Branches

The Continental Navy was established on October 13, 1775, when the Second Continental Congress authorized the acquisition of two armed vessels to intercept British supply ships. That date is now celebrated as the Navy's official birthday. The early Navy was outmatched and outgunned, yet it managed to harass British shipping and keep American morale alive during the Revolution's darkest hours.

The 19th century tested and tempered the Navy through the Barbary Wars, the War of 1812, and the Civil War. Admiral David Farragut's famous order at the Battle of Mobile Bay -- delivered in the face of Confederate minefields -- became a symbol of naval audacity. By the Spanish-American War, the Navy had grown into a genuine global force, projecting American power far beyond the western hemisphere.

World War II transformed the Navy into the most powerful maritime force in history. The Battle of Midway, fought entirely by carrier-based aircraft, broke the back of Japanese naval power and validated an entirely new way of fighting at sea. Today the Navy operates 11 nuclear-powered aircraft carrier strike groups, the most potent expression of forward-deployed military power on earth, alongside a submarine fleet that ensures strategic deterrence around the clock.

The U.S. Coast Guard traces its lineage to the Revenue Cutter Service, established by Alexander Hamilton on August 4, 1790 -- making it the oldest continuously operating maritime service in the United States. Before a permanent Navy existed, Revenue Cutters were the only federal maritime law enforcement and defense force. That dual identity, part military branch and part law enforcement agency, has defined the Coast Guard ever since.

Though the smallest armed service, the Coast Guard has fought in every major American conflict. Coast Guardsmen served as coxswains aboard the landing craft that carried troops onto the beaches of Normandy on D-Day. In Vietnam, Coast Guard vessels patrolled inland waterways under constant fire. In both World Wars, cutters provided vital convoy escort duty in the North Atlantic, hunting submarines and rescuing survivors of torpedo attacks.

Today the Coast Guard operates under the Department of Homeland Security during peacetime and can transfer to the Department of the Navy during wartime. Its missions span search and rescue, marine environmental protection, port security, icebreaking, and counter-narcotics operations. In a single year, Coast Guard crews rescue thousands of people, seize hundreds of thousands of pounds of illegal drugs, and respond to hundreds of pollution incidents -- largely out of public view.

The United States Space Force became the sixth branch of the armed forces on December 20, 2019, when President Donald Trump signed the National Defense Authorization Act. It is the first new military branch created since the Air Force in 1947, and the first military service dedicated entirely to a single operational domain since the modern joint force was conceived. Space Force was carved out of the Air Force Space Command, which had managed military space operations since 1982, and reflects a national recognition that space is no longer a peaceful sanctuary but a contested warfighting domain.

America's military relationship with space stretches back to the earliest days of the Space Age. Military satellites provided reconnaissance imagery during the Cold War that helped verify arms control treaties and prevented miscalculation between superpowers. The Global Positioning System (GPS), now used by billions of people worldwide for everything from navigation to financial transactions, was built and is operated by what is now the Space Force. During Operation Desert Storm, GPS-guided munitions and satellite communications gave coalition forces a decisive advantage.

The Space Force's primary missions include operating military satellites, providing missile warning for the homeland and deployed forces, conducting space domain awareness to track the tens of thousands of objects orbiting Earth, and protecting U.S. space assets from adversary interference. Its personnel -- called 'Guardians' -- are among the most technically specialized in the military, managing systems that the entire joint force depends on to operate. As China and Russia develop anti-satellite weapons, the Space Force's role in deterring conflict and ensuring freedom of operations in space grows more critical each year.