Philidor Defense

The Philidor Defense, also spelled Philidor's Defense, protects the e5-pawn with 2...d6 rather than with a knight. This keeps the c- and f-pawns free to advance, but Black develops no piece and the pawn on d6 blocks the dark-squared bishop. Ruy López had already preferred 2...d6 to 2...Nc6 in the sixteenth century, wishing to sidestep 3. Bb5. The name honors François-André Danican Philidor, who intended to follow up with ...f5 and strike at White's center.

The principal test is 3. d4, which threatens to open the position with dxe5. The most frequent answer, 3...exd4 (the Exchange Variation), concedes the center in return for easy development; after 4. Nxd4 Nf6 5. Nc3 Be7 and ...O-O Black has a cramped but resilient position, while the Larsen Variation 4...g6 fianchettoes the bishop instead. White can also offer material with 4. Bc4 (the Morphy Gambit) or 4. c3 (the Bird Gambit). The other strategy keeps the pawn on e5 with a strongpoint setup of ...Nd7, ...Be7 and ...c6, a structure Larry Kaufman likened to the closed Ruy Lopez. The Hanham Variation, 3...Nd7, runs into the awkward 4. Bc4, whereas the Nimzowitsch Variation, 3...Nf6, aims for the Lion Variation 4. Nc3 Nbd7 but permits 4. dxe5, after which queens often come off early. Some players therefore begin with 1. e4 d6 2. d4 Nf6 3. Nc3 e5. Black should avoid 3. d4 Bg4, the line of Morphy's 1858 Opera Game, because 4. dxe5 leaves White with active pieces and the bishop pair.

Philidor's own 3. d4 f5, the Philidor Countergambit, leads to open and tactical positions but is generally judged unsound, though it has periodically returned to practice. Its counterpart after 3. Bc4 is the Lopez Countergambit, 3...f5. In fact 3. Bc4 is the most played third move in the database; White may later transpose with d4 or keep things quieter with d3, and 3...Be7 4. c3 is the Steinitz Variation. 3. Nc3 aims for Be2 and kingside castling, or for Bf4, Qd2 and O-O-O.

The defense lost ground as positional understanding developed and had almost disappeared from elite chess by the First World War. Masters still use it occasionally as a less theoretical alternative to 2...Nc6, and it is widespread at faster time controls online, ranking among the most frequently reached named positions. Engines give White a slight edge, and White scores somewhat better in practice.