Nicknamed the “Old Reliables”, the 9th Infantry Division arrived in Vietnam in December 1966. Their shoulder sleeve insignia was an olive drab disc that boasted an octofoil horizontally divided into red and blue halves. The 9th were based in the Mekong Delta region (IV Corps), with the 2d Brigade forming the ground element of the Mobile Riverine Force. The bulk of the division departed from Vietnam in September 1969, though the 3d Brigade continued to operate in III Corps under the 25th Infantry Div. until October 1970.1
1. The Institute of Heraldry