On August 10, 1942 the U.S. Army's public-relations office issued a press release warning the public of "secret markers" that had been found on farm fields throughout the eastern United States. These markers were patterns formed by the arrangement of fertilizer sacks or the way a field had been tilled. From the ground they looked like nothing, but from the air they formed the shape of arrows, apparently created by Nazi sympathizers in order to guide enemy bombers toward military factories and airfields.

The Army simultaneously released three pictures showing these markers. But a few days later it was discovered that the "secret markers" were really just random patterns of no military significance, a fact the Army had known for months. More→

In 1943 the body of a British officer, Major William Martin, was discovered off the coast of Spain, near Huelva. British diplomats strongly requested that all documents found with the body be returned to them, and the Spanish government eventually complied. But upon examination, it was obvious the documents had been opened and read before their return. This was exactly what the British had hoped would happen, because Major Martin did not exist. He was part of a military hoax, codenamed Operation Mincemeat, designed to fool the Germans.

The British military had obtained a cadaver, chained a briefcase containing supposedly top-secret papers to its wrist, and dropped it in the sea off the coast of Spain. The plan was that the Germans, via the Spanish, would find the body and read the fake papers. The papers stated that the Allies' planned invasion of southern Europe would begin with an attack on Greece and Sardinia. In reality, the Allies planned to attack Sicily first. The hoax was successful. When the Allies launched their offensive on Sicily, most of the heavy German equipment had been moved to defend these other locations.

Ewen Montagu, the British officer who devised the operation, later wrote a book about it titled The Man Who Never Was. The book was subsequently made into a movie.

During World War II, the illustrator Hugh Troy was given a desk job stateside. He found it excruciatingly boring. So to amuse himself he began preparing Daily Flypaper Reports in the style of standard army regulations. These were counts, printed on official-looking paper, of all the flies trapped on flypaper in the mess hall during the last twenty-four hours. He analyzed the results according to wind direction, nearness to windows, nearness to the kitchen, length of the flypaper, etc. He then would mimeograph the report and slip it in among the other official forms submitted to headquarters each day.

After keeping this up for a month, he received a call from an officer in another comapny: "Lieutenant, Can you tell me the proper procedure for filing fly reports? We've been catching hell from the Pentagon for not sending them in."