Petroff Defence

After 1.e4 e5 2.Nf3 Nf6, Black answers the attack on e5 with a counter-attack on e4 instead of defending the pawn. The defence is solid and symmetrical, and its main trap is well known: after 3.Nxe5 Black should not copy with 3...Nxe4 at once, because an early Qe2 pins the knight against the king and threatens a discovered check that can win Black's queen. The correct order is 3...d6, driving the knight back with 4.Nf3, and only then 4...Nxe4. Black's knight on e4 is the centre of the opening. White tries to undermine it or exchange it, and Black tries to keep it supported.

The Classical Attack, 5.d4 d5 6.Bd3, is the main line. It leads to a symmetrical centre with pawns on d4 and d5. White usually castles and plays c4 to attack the d5-pawn, along with Re1 and Nc3 to pressure the knight on e4. Black has two main choices here. In the Marshall, 6...Bd6, the bishop is developed actively. In the Jaenisch, 6...Nc6 7.O-O Be7 8.c4 Nb4, the knight chases the bishop on d3. Two other fifth moves avoid this structure. The Nimzowitsch Attack, 5.Nc3, offers to exchange the e4-knight and often leads to opposite-side castling after Be3, Qd2 and O-O-O. The Cozio Attack, 5.Qe2, usually leads to an early exchange of queens and a quiet endgame. The Steinitz Attack, 3.d4 Nxe4 4.Bd3 d5 5.Nxe5, opens the centre at once. The Three Knights, 3.Nc3 Bb4, avoids the main Petroff structures altogether and gives a position closer to a Four Knights Game.

The Classical Attack, Part 1 of 2, is the first video and the best place to start. Its pawn structure and piece placement are the reference point for every other branch.