The winning set-up in a rook endgame a pawn up: pawn on the seventh, king in front of it, enemy king cut off on the next file.
Why it matters
The Lucena is the position every rook endgame with an extra pawn is trying to reach: pawn on the seventh, your king in front of it, the enemy king cut off on the next file. It is a win, and the method is a fixed sequence rather than a search.
The trick is that the king cannot simply step out — the defending rook checks it forever. The bridge solves that: your own rook comes to the fourth rank and eventually blocks the check, protected by your king.
See it on a board
The bridge. The rook on the fourth rank waits until the king reaches c5, then blocks the check on c4 where the king defends it, and the pawn promotes.
Checked: the position really has the feature described.
How to play it
- Get the pawn to the seventh, your king in front of it, and the enemy king cut off by at least one file.
- Put your rook on the fourth rank — that is the bridge.
- Walk the king out towards the checks. When the checking rook runs out of distance, block with your rook, protected by the king.
At each level
The same idea, said the way it is taught at each age.
Rook · ages 6–9
Pawn on the seventh, king in front, enemy king cut off: put your rook on the fourth rank and walk your king towards the checks.
Queen · ages 8–11
Getting to the Lucena is the real work. Cut the enemy king off first, before pushing the pawn, because a king that reaches the queening square holds the draw.
What goes wrong
- Pushing the pawn to the seventh before cutting the enemy king off.
- Walking the king out without the rook on the fourth rank, so the checks never end.
Questions people ask
- What if the enemy king is not cut off?
- Then it is usually the Philidor position and a draw. Cutting the king off is the condition that turns an extra pawn into a win.