Ruy Lopez that after the common retreat 4.Ba4, Black will have the possibility of breaking a future pin on his by playing ...b5. White must take some care not to fall into the Ruy Lopez, Noah's Ark Trap, in which Black traps White's on the b3-square with a ...a6, ...b5, and ...c4 pawn advance on the . Ercole del Rio, in his 1750 treatise "Sopra il giuoco degli Scacchi, Osservazioni pratiche dell'anonimo Modenese" (On the game of Chess, practical Observations by an anonymous Modenese), was the first author to mention 3...a6. However, the move became popular after it was played by Paul
Tactical wargame on the then-ongoing Cold War, called "Red Star/White Star: Tactical Combat in Western Europe in the 1970s". While the game was successful, Dunnigan was disappointed with it, citing difficulties in realistically portraying tactical combat in a tabletop board game. Dunnigan tried to take tactical games into a new direction in 1973 with "KampfPanzer" and "Desert War", which featured simultaneous movement, expanding on an optional rule for PanzerBlitz. Unfortunately, the quest for greater realism was having a price in complexity and "bookkeeping", or recording of moves on paper. Nonetheless, other tactical games on a man to man level were released with