The Lucena position: how to build a bridge

The Lucena position is the most important winning position in rook endgames. Your pawn is on the seventh, your king is on the queening square in front of it, and the defending king is cut off. It's a win, but the obvious tries don't work: your king is stuck in front of its own pawn, and stepping out invites a stream of checks. The answer is to "build a bridge" with your rook.

The method, played out

White to move. Step through the bridge.

Rook to the fourth rank

1.Rd4. The rook goes to the fourth rank, ready to build the bridge, and still keeps Black's king cut off. Many rook moves keep the win here, but a few just hang the rook: 1.Rd5? Kxd5 and 1.Rd2? Rxd2 throw it away.

King out

2.Kc7. Now the king comes out from in front of the pawn. Black starts checking: 2...Rc1+.

3.Kb6, 5.Kb5. Walk towards your rook, away from the checks. The rook on the fourth rank is waiting.

The bridge

6.Rb4. The rook blocks the check, right next to your king. No more checks, and the pawn queens.

The mistake at the end is going the wrong way: after 6.Kc5? Rxb7, the pawn falls, and it's only a draw.

The idea to remember

With your king in front of the pawn and the other king cut off: rook to the fourth rank, king out, and block the checks with the rook. Its drawing partner, the position the defender aims for instead, is the Philidor.

Train it

This is one of the endgame techniques OptiChess teaches as a walkthrough: the moves play themselves until a moment that matters, then you find the move, checked against the tablebase. More endings are in the chess endgame trainer.

Try it. Real positions, set at your level, every answer checked against the board. No account needed to start.

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