defense can also be used if the pawn is less advanced. In that case, the defending rook can occupy its fourth rank instead of its third rank and the defending king should be on at least its second rank. When the pawn reaches the rank of the defending rook, the rook moves to its eighth rank to check the opposing king from behind (assuming that the opposing rook is not on that rank). Philidor thought that the only way to draw was to keep the defending rook on its third rank until the pawn reached that rank and then attack from behind. In 1897, Max A.K.S. Karstedt (1868–1945) showed that this is not strictly true, and Johann Berger (1845–1933) expanded on that. There are other ways to draw; however, the alternate defenses are more complicated. See also Chess endgame Endgame tablebase Lucena position Rook and pawn versus rook endgame References Bibliography Further reading External links Interactive Endgame Simulation of the Philidor Position Video explaining the Philidor Position Chess endgames Chess theory