On a shield shaped like the head of a battle-ax, 2 3/8 inches (6.03 cm) in width overall divided diagonally (from upper left to lower right) into two parts, red and blue, separated by a diagonal yellow bar, a crusader's unsheathed sword point to top with white blade and yellow hilt, the blade fimbriated red where it crosses the yellow diagonal.
The crusader's sword (the "Sword of Freedom") was suggested by the shoulder sleeve insignia previously authorized for the United States Military Assistance Command, Vietnam, and the United States Army, Vietnam. The one diagonal refers to the numerical designation of the I Field Force. The sword "piercing" the red area alludes to the constant probing of enemy territory and positions and the driving back and crushing of enemy forces. The colors red, white and blue are the national colors of the United States, and the colors yellow and red, are those of Vietnam. The colors blue, red and yellow are also those of the three major combat arms: Infantry, Artillery and Armor. The silhouette of the shield is shaped like a battle-ax to symbolize the smashing power of the I Field Force and the constant combat readiness of its personnel to engage the enemy. The battle-ax shape, in itself, is also an additional I Field Force identification.
The shoulder sleeve insignia was approved on 5 October 1966. (TIOH Dwg. No. A-1-436)