The Lucena Position
Named after Luis Ramirez Lucena, author of a 15th century chessbook, this position's place in chess theory is as fundamental to chess as arithmetic is to our primary education. This position, however, does not appear in Lucena's work entitled, Repeticion de Amores e Arte de Axedres ( 1497 ). The Lucena deals with pawn promotion, the placement of rooks, the coordination between pieces, the importance of king position, and the usual exceptions when dealing with the A and H files.
Let's enumerate the salient points of this position:
- White is a pawn up. The pawn is passed and already on the seventh rank.
- The white king is in the way of the pawn. He needs to get off the queening square to make the promotion possible.
- The black rook is standing guard. It will attack the white king as soon as he steps into the open.
- The black king is also standing by, ready to help prevent the pawn promotion or even make its capture a possibility.
- The white rook is behind the passed pawn, though not directly, but it could be put to better use. Providing cover for the white king will be its role.
The climb to the summit begins with white pushing the black king away from the action by 1. Rd1+, Ke8. Now, there are two files separating the black king and the passed pawn. It will take the black king two moves just to have influence on the passed pawn and its queening square. In many rook and pawn endings, cutting off the king from the action is what makes the win possible.
Since it has been determined that the white rook will provide cover for the king, the question is where to put it. I have seen a rule of thumb that suggests, " to determine the queening square and count 5 ranks back. "
Let's give it a try with 2. Rd4, Ra1. Black is waiting. Play continues 3. Kc7, Rc1+ 4. Kb6, Rb1+ 5. Kc6 ( still protecting the pawn ), Rc1+ 6. Kb5 ... At this point, white is too far to support his pawn from attack but all is according to plan. The black king is still cut off from the action by the white rook. The play goes on 5... Rb1+ , and it seems that the pawn will be lost. Not really. White swings over his rook 6. Rb4 to negate the check and provide the necessary cover for the pawn to queen. The black king has now been released from his containment, but he is one square too far to harass the pawn, the point of white first move 1. Rd1+ . Black may continue with 6... Rb4+ 7. Kb4 ... , but black cannot stop the pawn from promoting. White wins.
The technique employed by white has been compared to " building a bridge. " This winning method does not apply when the passed pawn is on the A file or the H file. Otherwise, you can apply the technique when the passed pawn is anywhere from the B to G files.
There is, however, another exception to the rule. This pertains to the placement of the defending rook. If there are three files separating the defending rook and the attacking king, then this bridge-building will fail and the pawn will be lost if black plays correctly. Generally speaking, the three-file spread will allow the defending rook to attack the king from the side. When the king responds by approaching the rook ( to capture it or stop the checks ), the rook will swing across the three files and attack the passed pawn from behind. The attacking king would be too far and too slow to cover the same distance. I will leave that to you to figure out.