By the 1940s, the Parker Brother's board game, Monopoly, was being played all over the world, and in particular had become all the rage in Britain. But it was soon to be used for much more than just passing the time.
In 1941 the British Secret Service was looking for a way to help British airmen escape from Nazis POW camps. But how could they get them information and supplies without being caught? MI9 officer, Christopher Clayton Hutton, finally hit on the idea to conceal escape maps in board games. The Secret Service approached British manufacturer John Waddington Ltd. to make a special edition of Monopoly for the prisoners of war. Maps were hidden inside the game board, real money was mixed in with the play money, and compasses, files, and other objects to help soldiers escape were either hidden in the board or disguised as game pieces. Different maps were created, one for each of the regions around the six German camps, and the maps were printed on silk so that they would be durable but not make any noise (paper maps rustled too much). The Secret Service then created a fake charity group and distributed the games to the POWs through it. Before they left on missions, airmen were told that if they were caught they were to look for one of the games in their care packages; if it was a special edition Monopoly set, it would be marked with a red dot on the Free Parking space.
Although the exact number is not known, it is thought that these games helped some 10,000 POWs to escape from German camps. To those soldiers, the games were the ultimate Get Out of Jail Free card. Sadly, although there are a few of the silk maps in museums, none of the games survived; they were all destroyed after the war.