411 REFERENCE · Wikibooks
Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Nc3/3...Nf6/4. Bb5
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Four knights Spanish C48 Four knights game
Spanish game → Berlin defence (by transposition)
4. Bb5 · Four knights Spanish
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...Qd4, which forks the e4 pawn and White's knight, but in this line White's knight on c3 defends e4 and 6...Qd4 would win back nothing. However, Black can instead play 6...Nxe4!, sacrificing their knight for the pawn, because 7. Nxe4 Qd4 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.
Theory table
1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bb5
4
5
6
Symmetrical Variation
Bb5Bb4
O-OO-O
d3d6
=
...Bc5
O-OO-O
Nxe5Nxe5
=
Rubinstein Variation
...Nd4
Ba4c6
Nxe5d5
=
References
See also
Four Knights Game