This pin commemorates the formation of the 10th Mountain Division during the later years of WWII. To this day, the 10th remains the only US military division to be given specialized training for mountainous conditions. Immediately following WWII in 1945, the division was deactivated, just to be reactivated and deactivated once more in 1958, and finally was reactivated again in 1985. Since its reactivation, the division has become the single most deployed in the US military.