Start with the conclusion, work backwards to construct a proof
One of the best known wargames of World War II was one that the Japanese used in planning their proposed Midway operation. The game's plan took into consideration all of the known variables that might have bearing on the operation's outcome. What resulted was a matrix of probable U. S. forces available versus known Japanese forces and of probable U. S. tactics in the face of planned Japanese tactics. When play ended, the Japanese had lost the game. Since they had surprise and numerical superiority in their favor, this outcome was considered unacceptable. The rules of the game were adjusted (in the tradition, perhaps, of all wargamers) to produce the desired Japanese victory. Having vindicated themselves on the game map, the Japanese then proceeded to substantiate the verdict of the initial game design by suffering their first major defeat of the war."