A Bishop up is not Enough to Win - Rook's Pawn Endgame

A Bishop up is not Enough to Win - Rook's Pawn Endgame

FangBo
FangBo
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19

Hello,

I was playing a game a few minutes ago. After just 5 moves, my opponent fell into an opening trap and blundered a piece, which I happily snatched off the board with great delight. Openings however, is not the topic of this article. 

I went through the usual procedure of swapping off pieces and reducing the material down to an endgame situation, where I would be a piece to the good, and could simply nibble off all of my opponent's remaining pawns and get myself a queen. Well, this should be a sensible plan, but you have to be a little careful to leave enough material on the board to be able to deliver checkmate, which is what I thought I had done. 

The thing I was forgetting is that rook's pawns are the worst sort of pawns you can have in an endgame. They are so bad in fact that as many as 6 of them are incapable of defeating a lone king if he stands in the way. For example in this position:

And even if the strong king manages to muscle his way in front of the pawn, in the hope of shepherding the fledgling queen through to promotion, there are still drawing chances. These are based around imprisoning the strong king in the corner. Here is an example:


Now in these two cases above, the strong side is only ahead in pawns. It turns out that sometimes being as much as a bishop even, is not enough material to win the game. The defender can hold a positional draw only if the bishop is of the opposite colour square to the corner of promotion of the rook's pawn in question. This is what we would call a 'the wrong bishop'. Having the right coloured bishop is enough to win, because you can check the blockading king out of the way.
Back to my game... After several hours of carefully improving my position, I went too far with my simplification plan and lackadaisically pushed 46.g5?? which simultaneously removed one of my opponent's weaknesses and left me with only hideous rook's pawns -
It is the sort of move that is easy to play, but one that helps your opponent, and people play these moves quickly all the time. It is called a conditioned reflex.
 What both my opponent and I failed to see was that I had a wrong coloured bishop, and in fact any position where the black king stands in the corner is a textbook draw. Here is how the position arose:
Key points for strong side (in material up endgames):
  • Exchange pieces not pawns - It is a well known maxim. Leaving yourself with just a bishop and king versus a lone king leads to a draw. This is the extreme case of violating this rule. Normally a bishop and pawn versus king and pawn is enough to win, because you can force zugzwang and win their pawn, then promote by standard means, wasting a tempo here and there with the bishop. However if the pawn is a rook's pawn, then you should check what colour the corner square is. If it is the same colour as your bishop, then you can win. If not it is a draw.
  • Know when a pair of blocked pawns is your weakness or one of your opponents - You should aim to remove your own weaknesses by exchanging them off the board, and keep your opponent's weaknesses on the board. There is no point in trading a pair of pawns if they are a weakness of your opponent's. If they are blocked, they aren't going to run away. They are only another thing for your opponent to worry about, and you might even win the pawn outright if your king gets to a dominant position.
  • In the late middlegame, check the colour of your remaining bishop - to see what corner is the wrong corner. This will affect how you make exchanges as the game progresses, and should hopefully mean that you don't end up in a wrong bishop + rook's pawn endgame!
  • Do not hurry - While this does apply here, it is more of a general endgame maxim (discussed in detail in Shereshevsky's endgame strategy). If you have a piece, then you can make any number of waiting moves, while your opponent may be forced to push forward pawns and create weaknesses, or shuffle around with the king, when your own king can barge in and shoulder its way into a dominating position from where it can threaten to win enemy pawns. The point is, if your opponent is passive, you can tease them a little bit (making sure you don't get a 3 fold repetition), before committing to serious decisions like piece trades and changes in pawn structure.

I hope you enjoyed this brief article, and if you have had any endgames where you got an unexpected win in a drawn position feel free to post them in the comments below.

Cheerio!