Its the only thing they could do, and still could do. its still holds today, in the army they train you if your in an open field and a bomb goes off dive head first towrds it, so your helemt will take the better part of the burning. closer to the ground heat rises. sure if your right at the middle of the bomb your toast, but youll be toast no matter what you do there. the duck and cover thing will help from about a mile out or so.