First mass-marketed in 1934, Monopoly soon after played an intricate role in World War II for British POW's. While imprisoned, the British airmen held behind German lines were allowed packages from humanitarian groups. One approved part of the package was "games and pastimes" as it was believed that playing games made prisoners less troublesome.
Taking military advantage of this opportunity, the British created fake charities such as the 'Licensed Victuallers Prisoners Relief Fund' and the 'Prisoners' Leisure Hours Fund' to supply Monopoly games to prisoners that contained various tools to aid in escape. Compasses and files were disguised as playing pieces and money was masked in the form of French, German and Italian bank notes.
Able to conceal these pieces in a Monopoly game was easy, but the real reason Monopoly games were sought out was because of the company's ability to manufacture maps printed on silk. The company that manufactured the game (John Waddington LTD) was a leading innovator in printing on silk, a trait that the British secret service was searching for. Maps to help the prisoners navigate their way back to safety needed to be printed on material much hardier than paper. Silk maps wouldn't tear or dissolve in water. In addition to their durability, they were much lighter and didn't make noise while handling. The British secret service and Monopoly collaborated on the escape kit.
Prior to going on missions, members of the Royal Air Force were told that if captured, they should look for the Monopoly game care packages. A red dot was marked on the 'Free Parking Space' to distinguish the altered game. Once the soldiers retrieved the essential materials from the game, they were ordered to destroy it in order to keep it secret from the Germans.
It is estimated that the Monopoly games could have helped thousands of captured soldiers make their way to neutral countries and back home. (the exact number is unknown)