This is the M1 helmet variant used by the United States and South Vietnamese forces during most of the Vietnam War (1955-1975). The Mitchell / Vine Leaf pattern helmet cover and helmet combination was introduced in 1959. It was used until its replacement by the PASGT helmet in 1983.
From 1955 to 1964, the helmet liners were similar to the high pressure fiber and resin liners used in WWII and in the Korean War. In 1964 a new plastic liner was introduced which saw a simplification of the suspension and omitted the leather liner chinstrap seen on WWII and Korean war liners. The steel shell is equipped with an olive drab chin strap with quick release buckles and a ball detent to avoid injuring the wearers neck. The shell is also equipped with a reversible Mitchell/ Vine Leaf pattern helmet cover.
NOT USED IN WWII