Endgames can be convoluted. Many ideas are interwoven, which makes it hard to isolate pure endgame ideas or technical plans. However, if one looks for a specific idea and searches through the games, one can be surprised at finding it under different circumstances and in all kinds of situations. Direction matters, one should know what to look for. The series of articles started with last week's article aim at isolating one idea and concentrating on it and exploring how it works under different conditions. Last week we looked at queen and bishop (Q+B) endgames where one chessplayer could attack along the long diagonal. Today we will continue with the topic and include an example of how a long diagonal is important in Q+B as well as pure queen endgames. Many ideas in Q+B endgames are derived from queen endgames, so it is worth exploring the importance of the long diagonal in queen endgames too.
The following position is not easy to evaluate.
Black has more space on both flanks, his pieces are more active and the bishop on b1 is cut off from play. Black's only disadvantage is that his king is a bit weaker than the white king but how can white use it with the bishop on b1 doing nothing. It turns out that black king's being weak is the major point in evaluation. White starts an attack with a pawn storm on the kingside that opens up the b1-h7 diagonal through which the bishop on b1 will enter the game. Paradoxically, it is the black bishop on b3 that ends up out of play: it does not participate in the king's defense. Now that I look at the position more another element that strikes me and that comes in handy in evaluating is that the black pawns are on the same color squares as the bishop. This certainly helps white because these pawns can be attacked.
Up until now both players have played extremely well! White undermined the e4-pawn, while black defended the f5 pawn by retreating the bishop and keeping the queen on the active c5-square. White pushed the pawns on the kingside and after black weakened the back ranks, white infiltrated with the queen. What is the threat now? To win the a6-pawn? No. The real threat is to take control of the long diagonal a1-h8. If the white queen gets there black will not be able to cover the weaknesses on f6 and e5. Going through many examples like this one can develop the feeling as to what is important in Q+B endgames.
After black allowed the white queen to get on the long diagonal black's position collapsed.
The control of the long diagonal comes from queen endgames. It works for Q+B endgames well too but I think the origin is in pure queen endgames with no bishop present. As an example I would like to refer to the position that A.Soltis uses in his excellent new book "What it takes to become a chess master".
He asks the reader to evaluate the position mentioning that an inexperienced player will give an advantage to white due to an extra pawn. However, the experienced player knows that one of the major decisive factors of queen endgames is how far the passed pawns are advanced. In this case both sides have far advanced passed pawns, so it does not really help our case here. Furthermore, a master will notice another important feature of the position, and it is as Soltis puts it: "Believe it or not, it's a diagonal". The a8-h1 diagonal. Whoever controls the diagonal also threatens/defends the white king and controls the promotion square of the a-pawn. Kramnik finds a brilliant idea that wins the game right away. Particularly, the one can see Kramnik's idea in a sideline to the black's 45th move.
We discussed the topic of importance of the long diagonal in endgames. Particularly, we looked at an example of a Q+B endgame and a queen endgame. Next week we will continue exploring Q+B endgames where one has to pay attention to shorter diagonals, such as a2-g8 or b1-h7.