Escape and evasion map printed on playing cards distributed to Prisoners of War which could be soaked and pealed apart revealing the escape map. Many of the maps of the Pacific region were printed by the US Army Map Service, while the UK was responsible for many of the European Theatre maps. Many of the US Navy charts were folded in envelopes and distributed to the air crews before a mission, and to be turned in when the mission was successfully completed. They were called "drift charts" by the Navy, "...since their prime purpose was to indicate to aircrews survivors in their life rafts
Aviation in World War I reveal their positions to aircraft, as they (the soldiers) found distinguishing between friend and foe problematic. Reconnaissance flying, like all kinds, was a hazardous business. In April 1917, the worst month for the entire war for the RFC, the average life expectancy of a British pilot on the Western Front was 69 flying hours. Typical 1914 aircraft could carry only very small bomb loads – the bombs themselves, and their stowage, were still very elementary, and effective bomb sights were still to be developed. Nonetheless the beginnings of strategic and tactical bombing date from the earliest days of the war.