The 158th Infantry Regiment was originally part of the Arizona National Guard and assigned to the 45th Division. In 1941 they were sent to the Panama Canal Zone to guard that vital installation. While there they were detached from the 45th and became an independent regiment. They also adopted the nickname "Bushmasters" after the tropical snake. The unit was committed to combat at Dutch New Guinea and Luzon in the Philippines. The insignia was not officially approved during the war. The unit was inactivated in 1946, but the design was later authorized for the 258th Infantry Brigade.

The patch is known to exist in several color variations, which are believed to indicate component units of the Regimental Combat Team. These include orange (engineer), red (artillery or engineer), blue (infantry) and green or maroon (medical). The documentation regarding colors and branches is limited and therefore somewhat uncertain.

Felt with White Border (Courtesy: Bob Capistrano)	Felt with Black Border (Courtesy: Bob Capistrano)	147thField Artillery Battalion 1279th Combat Engineers Felt with Red Cotton Background Philippine Made (Courtesy: Sandra Calder)

For more informaiton on the many variations that exist with this patch see the great article by Steve and Dave Johnson 158th RCT Variations The Trading Post (LXII Oct-Dec 2003):11-14. It includes some 20 photographs of different variations.