To expand a bit. The military issued each GI a "duffle bag" ("sea bag" for sailors) into which all of his personal possessions had to fit. When he changed station, or was rotated home, everything he owned had to fit in that duffle bag. He couldn't dump other stuff, as he had to show that he still had his clothing issue, and there was little room for souvenirs.
Note that items like weapons, helmets, ammo belts, field jackets, and the like were unit supplies, not personal belongings, and were left behind with the unit when the GI transferred.
Jim