Lone Pawn in Rook Endings: Number of Files Needed to Cut the King Off (Part 1)
Rook endings are by far the most common ones in chess. This is why I believe an article about them is long overdue. Here, we will be looking at an important ending, R + P vs R but with the defender's king cut out by a file or two. This appears in practical endings fairly often.
Memorising the winning/drawing methods and evaluations of basic positions are essential in helping one assess more complex endings. This is because when the player calculates variations in a complex position, he does not need to go too deeply before arriving at a known position in his repertoire of endgames.
Therefore, before going further, please familiarise yourself with two basic positions, the Lucena position and the Philidor position.
Lucena position: When the black king is not in front of the white pawn, white wins this game.
Philidor position: When the black king is in front of the white pawn, black can hold the draw.
If you do not know these positions, I recommend that you take a look at two videos by International Master John Bartholomew where he gives very easy-to-follow explanations on the Lucena position and the Philidor position.
Now that you know these two basic positions, let me present you a defensive idea in R+P vs R, the frontal attack. In the following position, it looks as though black is about to convert this into a Lucena as his king chaperones his pawn while the white king remains cut out. If the pawn has already crossed the fourth rank, the winning technique will be trivial. Given that it is rare for the pawn to be on the second or third rank when the black rook is already in a position to mount the frontal attack, I will only cover positions where the pawn is on the fourth rank.
We will now take a look at a similar position where the defender's king is cut off by two files.
If all the pieces were shifted one file to the attacker’s left in the earlier two positions, the winning/drawing methods and the results would still have been the same. From here, we learn an important lesson: When trying to win with a lone central or bishop pawn in rook endings, the enemy king must be cut off by at least two files for a win.
Before I end this article, I would like to bring a deceptively similar position to your attention.
That defensive idea is sometimes known as the short side/long side defence. If you are not familiar, IM John Bartholomew has got you covered again. Click here to see his video.
It would seem that in this special case, two files is not enough for the win. However, there is a new feature in the position: The black king is at the edge of the board, which allows for some mating ideas.
I hope you found this article instructive. This idea (number of files required to cut the king off) will be covered for knight and rook pawns very soon. If you are interested, please follow my account.
