The 11th Infantry Brigade (Light) was an infantry brigade of the United States Army. It was first formed as part of the United States Army's 6th Division during World War I. It is best known for its service with the 23rd Infantry Division (Americal) in the Vietnam War. It was active from 1967 through 1971. The brigade is known for its responsibility in the infamous My Lai Massacre and many of its former servicemen were interviewed in the iconic documentary Four Hours in My Lai.