The USMC did not wear nearly as much insignia as the Army. The unit patches were not introduced until mid-1943, and were authorized for wear on the Forest Green Wool Service Uniform, shirts and field jackets. The rank and service stripes were only worn on the "wools".

Field uniforms rarely, if ever had any insignia on them. Rank stripes were applied with black ink and a stencil, and unit patches are can be found on a handful of field jackets (M41). Fighting the Japanese dangerous enough. Doing it with bright red patches on your sleeves was suicidal. Thus, if you are doing Living History/ Reenacting, or making a movie, it is historically incorrect to have patches sewn on green or camouflage "Utilities/ dungarees". This insignia was essentially only worn on dress/ service uniforms.