The Trout Memo, written in 1939, is a document comparing deception of an enemy in wartime with fly fishing. Issued under the name of Admiral John Godfrey, Britain's director of naval intelligence, according to the historian Ben Macintyre it bore the hallmarks of having been written by his assistant, Ian Fleming.
The memo reads, in part: "The Trout Fisher casts patiently all day. He frequently changes his venue and his lures. If he has frightened a fish he may 'give the water a rest for half-an-hour,' but his main endeavour, viz. to attract fish by something he sends out from his boat, is incessant." The memo goes on to describe numerous ways that the enemy, like trout, may be fooled or lured in.
One idea from the memo was broadly similar to Operation Mincemeat, a World War II plan to convince the Germans that the Allies would attack Greece rather than Italy in 1943, although that idea was developed by Charles Cholmondeley in October 1942.