Lewis Gambit

The Lewis Gambit arises when White answers the Classical Variation, 2...Bc5, with the immediate 3. d4. Instead of preparing the advance with 3. c3, as in the Philidor Variation, White pushes the d-pawn at once. This breaks the symmetry and gains time against the bishop on c5. It shows the drawback often attributed to 2...Bc5, namely that White can always carry out the d-pawn advance first. The pawn on d4 is unsupported, so Black may simply take it. The play then turns on whether White's development and open lines make up for the material.

The usual reply is 3...exd4, chosen in about three games out of five, and White scores well after it in online play. Capturing with the bishop, 3...Bxd4, is the main alternative and gives nearly even results. Engines judge the position balanced. They also rate 3...d5 highly, a central counterstrike that challenges e4 and blunts the bishop on c4. The passive 3...d6 is rare and turns out badly for Black. Overall the gambit is a minor branch of the Bishop's Opening rather than a mainstream choice.