Philidor position

The Philidor position (or Philidor's 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-rank 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, "[The Lucena and Philidor positions] are the most important positions in this type of endgame [...] and in endgame theory."

The diagram shows an example of Philidor's position. The important characteristics of the position are (from the point of view of the defender):

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 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 (...Rc2–Ra2–Rc2), White can do the same (Ra3–Rh3–Ra3). With 3...e3, Black threatens to advance with Kf3, and if he is unopposed, checkmate with the rook or advance the pawn. (A passive defense does not work.)

Since now Black's king cannot move to e3, it is safe to move the rook away to the far end of the board (the defender's seventh or eighth rank). 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: