US WW1 USMC Wool overseas wedged cap

A wool OD "overseas" cap replaced the "Montana" campaign hat in 1917, and was, worn in the rear areas of France. The new corps insignia disc was worn on the left side. Modeled after a French cap, the 1918 overseas cap was later to become the field or garrison cap and in 1940 it was authorized for wear in the U.S. Then a cord was added in the color of the wearer's branch of service. Officers wore yellow cords until 1940 when the cord was changed to a gold and black braid.

In 1918 American Doughboys serving in France needed headgear that was comfortable to wear, yet could be stored in the pocket when the helmet was donned. The "Montana Peak" campaign hat proved to be a storage problem.

To replace the service and campaign hats, the AEF copied the French Bonnet de Police, an envelope-style fatigue headgear, and created the overseas cap, the predecessor to the garrison cap authorized in 1940 for wear in the US. In 1918, three different versions of the overseas cap were issued. It is not uncommon to see photos of units with individuals [un-uniformly] wearing each of the styles.