Activated in 1915, as the 173rd Infantry Brigade, the unit saw service in World War II but is best known for its actions during the Vietnam War. The brigade was the first major United States Army ground formation deployed in Vietnam, serving there from 1965 to 1971 and losing 1,533 soldiers. Noted for its roles in Operation Hump and Operation Junction City, the 173d is best known for the Battle of Dak To, where it suffered heavy casualties in close combat with North Vietnamese forces. Brigade members received over 7,700 decorations, including more than 6,000 Purple Hearts. The brigade returned to the United States in 1972, where the 1st and 2d Battalion, 503d Infantry, were absorbed into the 3d Brigade, 101st Airborne Division (Airmobile), and the 3d Battalion, 319th Field Artillery was reassigned to Division Artillery in the 101st. The remaining units of the 173d were inactivated.