Philidor position
The Philidor position is a chess endgame involving a drawing technique for the defending side in the rook and [pawn versus rook endgame]. This technique is known as the third- defense due to the positioning of the defending rook. It was analyzed by François-André Danican Philidor in 1777. Many rook and pawn versus rook endgames reach either the drawn Philidor position or the winning Lucena position. The defending side should try to reach the Philidor position; the attacking side should try to reach the Lucena position. Grandmaster Jesús de la Villa said, " are the most important positions in this type of endgame and in endgame theory."
Description
The diagram shows an example of Philidor's position. The important characteristics of the position are :- The defending king is on the 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.
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 in which each side is 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.