Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Nc3/3...Nf6/4. Bb5

This position may arise from 4. Bb5 in the Four knights, or 4. Nc3 in the Berlin defence. This position is quite even and drawish.

White threatens to take Black's knight on c6, which would leave the e5 pawn undefended. It's worth considering whether White can win a pawn in this way, e.g. 4...a6 5. Bxc6 dxc6 6. Nxe5. In the Spanish, Black often has a tactic to recover the pawn, 6...Qd5, which forks the e4 pawn and White's knight, but in this line White's knight on c3 defends e4 and 6...Qd5 would win back nothing. However, Black can instead play 6...Nxe4!, sacrificing their knight for the pawn, because 7. Nxe4 Qd5 forks the two white knights and recovers the material. Therefore, White needs to do a bit more to be in with a chance to capture e5 and hold onto it, such as defending e4 with a pawn.

4...Bc5 is the classical response. Black develops their bishop and starts to pressure f2. This actually gives Black a different way to tactically defend e5 in the event of Bxc6 & Nxe5. White usually castles 5. O-O, or plays the centre fork trick, Nxe5 Nxe5 d4.

4...Bb4 is the double Spanish and the main line today. The game may stay symmetrical for a few more moves.

4...Nd4 is the Rubinstein variation.

For explanation of theory tables, see theory table and for notation, see algebraic notation.

1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bb5

When contributing to this Wikibook, please follow the Conventions for organization.

Wikipedia has related information at Four Knights Game.

• Modern Chess Openings 15th ed, 2008. Nick de Firmian. Random House, New York. ISBN 0-8129-3682-5.

• Nunn's Chess Openings. 1999. John Nunn (Editor), Graham Burgess, John Emms, Joe Gallagher. ISBN 1-8574-4221-0.