The creator of the popular candy, "melt in your mouth, not in your hand", Forrest Mars Sr. spied them in the Spanish Civil War. Soldiers ate chocolate dragees in a hard shell of tempered chocolate that does not melt and does not stain your fingers.
Production of M & M's began in 1941, the year, and they became so popular that they have entered the food supply of American soldiers during the Second World War.
via factroom.ru