US Army

The US Army was a branch of the military of the United States of America.

History
During the American Civil War, the Union Army fought against the Confederate States of America. (COMIC: Backtime)

During the Korean War in 1950, the US Army fought the Red Chinese. (COMIC: The Good Soldier)

In 1958, during the Cold War, Colonel Stark of the US Army made a deal with the Viperox Lord Azlok to destroy the Soviet Union. Stark was convinced by the Tenth Doctor to turn against the Viperox. (TV: Dreamland)

In 2017, the US army was at a standstill with the Chinese army and the Russian army when in a war zone, Turmezistan, a 5000 year old pyramid appeared overnight. (TV: The Pyramid at the End of the World)

Behind the scenes
Beetle Bailey, the titular character from Beetle Bailey, appeared in the game Basil Brush goes Rent Collecting. Although in his home series, he is said to be part of the US Army, this is not explicitly shown in the game.