The cap is derived from the "M-35" or "M-37" Daisy Mae hat. The Daisy Mae hat first appeared in 1919 and was used on a large scale by the civilian conservation Corps in the 1930s. It was replaced in the 1940s by the HBT version of the hat. The surplus stock was issued to rear personnel and prisoners of war. Perhaps for the convenience of identification, quite A few hats have had their brims cut off, leaving only a part of the brim and re-stitched to look a bit like an A-3.