A French Army unit is on patrol in pre-Vietnam IndoChina in July 1954 during the First Indochina War. The captain of the patrol curses the land when they see nothing. Then, the unit is suddenly ambushed by hundreds of Vietminh soldiers who kill the officers and, although the unit kills many Vietminh, it is eventually overrun. One Vietminh officer, Nguyen Huu An, hypothesising that if they take no prisoners the French will eventually stop sending troops, orders the execution of all surviving French soldiers.
Eleven years later, Lieutenant Colonel Hal Moore (Mel Gibson), a dedicated U.S. soldier, is deeply committed to training his troops, who are preparing to be sent to Vietnam. The night before their departure, the unit's officers hold a party to celebrate. Moore learns from a superior officer that his unit will be known as the 1st Battalion / 7th cavalry regiment. He is disquieted because the 7th Cavalry regiment was the unit commanded by General George Custer in the 19th Century when he and his men were slaughtered at the Battle of the Little Bighorn in 1876. Moore is also dismayed because President Lyndon B. Johnson has decreed that the war would be fought "on the cheap," without declaring it a national emergency. As a result, Moore believes he will be deprived of his oldest, best-trained soldiers (a formal declaration of war