Evasion charts or escape maps are maps made for servicemembers, and intended to be used when caught behind enemy lines to assist in performing escape and evasion. Such documents were secreted to prisoners of war by various means to aid in escape attempts. During World War II, these clandestine maps were used by many American, British, and allied servicemen to escape from behind enemy lines. Special material was used for this purpose, due to the need for a material that would be hardier than paper, and would not tear or dissolve in water.