The Army also routinely deploys overseas to help train friendly nations. Here, soldiers from Charlie Company, 2nd Squadron, 38th Cavalry Regiment conduct Fire Phobia Training during a Kosovo Force Mission Rehearsal Exercise at the Joint Multinational Readiness Center in Hohenfels, Germany, January 21, 2014.
The Army also has its own special-operations team, the Army Rangers, who trace their lineage back to colonial times.
The US Army even has its own parachute team.
The Army also includes airborne divisions. Here, paratrooper Staff Sgt. Travis Surber, a paratrooper with the 173rd Brigade Combat Team's Battle Company of the 2nd Battalion, 503rd Infantry Regiment, parachutes out of a C-130 Hercules Transport Aircraft and into the Ukraine sky.
next slide will load in 15 secondsSkip AdSkip AdSoldiers practice repelling out of a Black Hawk helicopter at Fort Hood Air Assault School.
A Sikorsky UH-60 Black Hawk helicopter drops off a soldier. Black Hawks have been in service since 1979 and cost around $21.3 million.
Members of the Army National Guard help serve in peacekeeping missions around the world and aid US citizens during natural disasters. Here, a member of the Louisiana Army National Guard helps a child evacuate from flooding caused by Hurricane Isaac in 2012.
The Army has also functioned as a police force in war-torn areas. Two soldiers here provide security during a foot patrol in Ramadi, Iraq.
US Army self-propelled 155mm Howitzers assigned to the 7th Corps head toward the Kuwaiti border to force out Iraqi forces.
next slide will load in 15 secondsSkip AdSkip AdThe Army had a central role in Operation Desert Storm, the US-led mission to liberate Kuwait from Iraq in 1990-1991. Here, troops from the Army's 7th Corps huddle with protective gear, fearing a chemical-weapons strike by Saddam Hussein after the US started bombing Iraq.
Here, as fellow troopers aid wounded comrades, the first sergeant of A Company, 101st Airborne Division, guides a medevac helicopter through the jungle foliage to pick up casualties suffered during a five-day patrol near Hue in Vietnam in April 1968.
The Army has few fixed-wing aircraft, but it operates many kinds of rotary-wing aircraft. Here, US Army helicopters drop off American soldiers during an offensive against the Viet Cong during the Vietnam War.
President Harry Truman desegregated the Army in 1948. The Korean War was the first major conflict to have integrated units.
The Army also fought alongside the Marines in the Pacific against Japan. Here, infantrymen advance alongside an M4 Sherman tank in the Solomon Islands.
next slide will load in 15 secondsSkip AdSkip AdThe 442nd Regimental Combat Team, composed almost entirely of American soldiers of Japanese descent who volunteered to fight, won acclaim for its bravery during World War II. It is the most decorated force in US Army history.
The US Army troops were the bulk of the American force that came ashore during the D-Day invasion on June 6, 1944.
On November 11, 1918, the Armistice of Compiègne was signed between the Allies and Germany, effectively ending World War I. Here, soldiers celebrate the war's end.
US soldiers in France in 1918 wearing gas masks.
World War I was marked by the horrors of trench warfare and poison gas. Many trenches on the European front were plagued with rat and lice infestations and were breeding grounds for disease. Here, US troops stand in a trench in 1915.
next slide will load in 15 secondsSkip AdSkip AdThe Army began acquiring fixed-wing aircraft in 1910. Here, Army planes fly over Manhattan in 1939.
One of the most famous Army units was Teddy Roosevelt's "Rough Riders." They are pictured here after the Battle of San Juan in 1898.
Some of the first pictures of the US Army are of Union soldiers during the Civil War. Here's a photo of soldiers camping along the west bank of the Rappahonnock River at Fredericksburg, Virginia, during the Battle of Chancellorsville.