Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...Nd4

With this knight manoeuvre, Black gives up the defence of e5 and instead counter-attacks White's bishop.

4. Nxd4 is almost always played, and after 4...exd4, Black will have gained some space and the pawn on d4, which is not so easy for White to dislodge, will inconvenience White's queenside development. However, this comes at the cost of doubled pawns and falling behind on their own development. White usually castles and closes the centre with d3.

4. Bc4 is an uncommon alternative. White moves the bishop out of harms way, and since there is no knight on c6 to pressure, it may as well move onto the diagonal aiming at f7, where it would like to be anyway. Black usually initiates the knight trade, 4...Nxf3 5. Qxf3.

Bird's defence is named for Henry Bird, an English chess player who played it extensively in the 1870s.

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

1. e4 e5 2. Nf3 Nc6 3. Bb5 Nd4

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Wikipedia has related information at Ruy Lopez

• Kasparov, Garry, & Keene, Raymond 1989 Batsford chess openings 2. ISBN 0-8050-3409-9.