Forrest Mars Sr. was inspired to create the now famous M&M chocolate candies when he saw soldiers fighting during the Spanish Civil War. The soldiers were eating chocolate pellets with a hard shell of tempered chocolate. This prevented the chocolate inside from melting and them getting sticky fingers.
M&Ms started production in 1941, and their popularity and their shell were so popular that they, in turn, were used by US soldiers during World War 2! Who knew that M&Ms had such a violent beginning.