Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...a6/4. Ba4/4...Nf6/5. O-O/5...Nxe4

Black takes the free pawn. However, while Black's king remains in the centre, they must navigate the danger of an open e-file carefully, and White can eventually recover the e-pawn.

How is White to recover the pawn?

The natural 6. Re1?!, intending 6...Nc6 7. Nxe5, is in fact a very minor sideline. Black's knight can retreat to c5 instead, hitting the bishop and forcing White to trade it for the c6 knight. After 6...Nc5 7. Bxc6 dxc6, Black is doing well compared to the Exchange variation: White lost a tempo moving the bishop to a4 then back to c6, and the disappearance of the centre pawns favours Black's bishop pair.

Now that Black's rejoinder Qd4 wouldn't come with a fork, White may want to try 6. Bxc6?! dxc6 7. Nxe5 to grab the pawn back. However, Black can take the initiative by targeting the undefended white knight on e5, and White soon finds themselves behind in development (e.g. 7...Qf6 8. d4 Bd6 and White is out of good ways to defend the knight. Qh5? g6!, while Re1 drops the f2 pawn).

Therefore 6. d4 is the mainline. White controls c5 (preventing Nc5) and threatens Black's e5 pawn. If Black takes it 6...exd4, the Riga variation, they run into complications from Re1 due to opening their e-file with their knight and king still on it. Therefore the continuation is usually 6...b5 7. Bb3 d5, and White gets the pawn back 8. dxe5.

For explanation of theory tables, see theory table and for notation, see algebraic notation.. 1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Nxe4

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