The Philidor position usually refers to an important chess endgame which illustrates a drawing technique when the defender has a king and rook versus a king, rook, and a pawn, though it can also refer to a position in the queen versus rookendgame or a position in a rook and bishop versus rook endgame. In the case of a rook and pawn versus a rook, is also known as the third rank defense, because of the importance of the rook on the third cutting off the opposing king. It was analyzed by François-André Danican Philidor in 1777. Many rook and pawn versus rook endgames reach either the Philidor position or the Lucena position. If played accurately the defending side tries to reach the Philidor position; the other side tries to reach the winning Lucena position. Jesús de la Villa said " is perhaps the most important position in endgame theory". Philidor analyzed many positions, some of which have his name associated with them.
Philidor position, rook and pawn versus rook
The diagram shows an example of Philidor's position. The important characteristics of the position are :
The defending king is on the queening square of the pawn. The pawn can be on any.
The opposing pawn has not yet reached the defender's third rank.
The opposing king is beyond the defender's third rank.
The defender's rook is on the third rank, keeping the opposing king off that rank.
Black would like to get his king to the e3-square and threaten checkmate to force the white king away from the queening square of the pawn, e1. The white rook on the third rank prevents that. If Black checks with the rook from the side, White simply keeps the king in front of the pawn by alternating between squares e1 and e2. If Black offers an exchange of rooks White should take it, since the resulting king and pawn endgame is drawn. So Black's only winning chance is to advance the pawn. The basic idea for the defender is to keep his rook on his third rank until the pawn advances to that rank, then check the opposing king from behind. Here is a possible continuation: If 1...e3, advancing the pawn immediately, then 2.Ra8 draws since Black's king cannot escape checks without losing the e-pawn, when the resulting position with each side playing with a king and a rook, is a draw. There is little else for Black to try. If Black retreats the rook, the white king can advance, drawing easily. If Black shuffles, White can do the same. With 3...e3, Black threatens to advance with Kf3, and if he is unopposed, checkmate with the rook or advance the pawn. Since now Black's king cannot move to e3, it is safe to move the rook away to the far end of the board. Note that 4.Rb4+ loses immediately to 4...Kf3 when Black will checkmate or force the exchange of rooks followed by...Kf2 and promotion of the pawn. The black king cannot hide from the checks without giving up the pawn; nor can he approach the rook: 7...Kg5 is also answered by 8.Re8. Black is forced to play...Kd4 or...Kf4, making no progress. The defender's rook must be on his seventh or eighth rank to employ the Philidor defense. To sum up the defense: the defender should keep his king in front of the opposing pawn and keep his rook on the third rank until the pawn advances to that rank, then go to the far end of the board and check the king from behind. If the attacker tries to get his king to his sixth rank by moving his rook to that rank first to block the checks, the defender simply exchanges rooks and has a drawn king and pawn versus king endgame. Philidor actually studied a position that leads to the type of position above. In the diagrammed position, if it is Black's turn to move, he moves and then his rook will reach his third rank, and the position is basically the same as the diagram above, with colors reversed, e.g. 2. Ke6 Rb6+ 3. Kf5 Rc6 establishes the standard defensive setup. If White is to move, he wins with accurate play by 2.Ra8# was threatened. Moving the king to the "short side" of the pawn is relatively better than to the other side. etc., and wins. Note that Black reaches a draw after 1.Kd6 Re4!, for example 2.Ke6 Kf8 3.Ra8+ Kg7 4.Kd6 Kf7 and White cannot break through. Philidor's 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 ,. 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 showed that this is not strictly true and Johann Berger expanded on that. There are other ways to draw; however, the alternate defenses are more complicated.
Queen versus rook
Philidor studied many endgame positions. Another one that he studied in 1777 involves a queen versus a rook. If Black is to move in this position, he quickly loses his rook by a fork. For example, thus forking the rook on b1. If, on the other hand, White is to move in this position, he would like to be in this position except with Black to move. This can be accomplished by triangulation: and now it is back to the same position but Black has to move ,. Nunn describes that with the pieces in the center of the board the queenought to force the rook towards the Philidor position. Nunn describes the various retreat positions for the rook, the "fourth, third, second" rank defenses, then the "Philidor position". It is usually easy for White to force Black into the Philidor position. With Black to play in the Philidor position, the rook can be won in a few moves.
Another famous position studied by and named after Philidor is in the ending of a rook and bishop versus a rook. White wins because his king has reached the sixth rank and black's king is poorly placed . If this type of position arises, it is usually because of inferior defense. Nevertheless, it is tricky to win.
