The Twelve-cent Prexie
Sheet stamp use
Armed forces personnel and certain others serving outside the continental United States could send first class letters and postcards free to anyone in the U.S. or territories and possessions from April 1, 1942 through the end of 1947. This 1944 cover from a serviceman in Scotland is more of a package than a letter, so apparently was charged domestic first class postage for four ounces.