World War II saw the rapid development of all aspects of war. From Germany's opening Blitzkrieg to the importance of air power, to the use of submarines to disrupt supply lines, both sides used just about every trick in the book to dominate the battlefield.
But that's not the all they did - espionage took giant steps forward during this conflict, from the fake Army at D-Day to Operation Mincemeat.
Operation Mincemeat was part of Operation Barclay, a disinformation plan by the Allies to confuse the German and Italian forces about the planned invasion of Italy from North Africa.
Mincemeat was a plan to give the Axis forces fake "Top Secret" documents, by planting them on a corpse that was to wash up on a beach in Spain.
Of course, to accomplish this deception the British had to account for everything. The corpse, which was a homeless man named Glyndwr Michael who had died after eating poison, had to have a complete personal and military history created.
You can watch a short video about this incredible plan on the latest Things You Might Not Know video: