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| Elementary endgames (Part 6) | |||||
| When an endgame position is an exception, there is often a Rook's Pawn involved. | |||||
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In our previous article on elementary endgames (Part 5; see the link box at the bottom), we discussed some of the ideas behind King and Pawn vs. King. We saw that a King in front of its Pawn and having the opposition against the enemy King was almost always a win. There were two exceptions, shown again in the following diagrams. Both positions are draws.
In our discussion of Draws (see the link box again) we used the following position to illustrate triple repetition. In spite of White's great material advantage, the game is drawn.
In another article on elementary endgames (Part 3 : Piece without Pawns vs. Pawn without pieces; link box again), we discussed the following positions. On the left, an unaided Knight manages to cope with a King and Pawn until the Pawn has reached its seventh rank. On the right, White is unable to win despite having the overwhelming advantage of a Queen against a single Pawn.
What do these examples all have in common? The Pawn is a Rook's Pawn, which means a Pawn on the a-file or the h-file. Unlike Pawns on the other files, a Rook's Pawn hugs the side of the board. This provides a natural barrier which nearly always results in exceptional endgame positions. Let's look at some more of those exceptions.
Although the Rook's Pawn is usually an advantage for the defense of a difficult position, it occasionally aids the offense. The following diagram shows a rare case of a King and Knight giving checkmate.
White forces checkmate with 1.Kc2 Ka1 2.Nc1 a2 3.Nb3. In the following position the White Knight and Pawn win against the superior force of King and Knight.
After the surprising sacrifice 1.Ng7+ Nxg7, the Pawn marches to its promotion square with 2.h6 Kf8 3.h7. The Queen will overpower the Knight in a few moves. The two preceding positions were tactical curiosities, but the following is a typical endgame which is seen frequently. Let's call it Bishop of the wrong color.
Note that the Bishop moves on the dark colored squares, but the Pawn's promotion square on a8 is light colored. This makes it the wrong color. A typical sequence is 1.Kb5 Kb7 2.a6+ Ka8 3.Kb6 Kb8 4.Be5+ Ka8. White can't approach the Black King without allowing stalemate, and the Black King can never be driven from the corner. What a difference a Bishop of the right color makes! The following diagram is similar to the previous. The only difference is that the Bishop is now on a light colored square, the same color as the promotion square of the Pawn.
After 1.Kb5 Kb7 2.Be4+ Ka7 3.a6 Kb8 4.Kb6, the Black King is forced from the corner. White gets a new Queen and wins easily. The weak King draws if it can reach the Knight's file in front of the remaining Pawn, b8 in our example. The battle to reach the safe area can be complicated and has its own tactical twists and turns. The following example is by a famous endgame composer.
After 1.Be6 Ke7 2.h6, the Bishop can't be taken. If Black continues 2...Kf6, then 3.Bf5 Kf7 4.Bh7 establishes a shield which keeps the Black King out of the corner. Now after 4...Kf6 the White King forces the Black King to move away from the critical area. After 5.Kf4 Kf7 6.Kg5 Kf8 7.Kf6 Ke8, White wins. In the following position, White must again approach the corner to force the Black King away. Caution is required.
If White plays 1.Kc5, then 1...b6+ forces White to recapture. If the Bishop captures with 2.Bxb6+, the Black King reaches the safe area with 2...Kb7. If the Pawn captures 2.axb6+, we have a position with a Knight's Pawn which is also a draw after 2...Kb7. If White plays 1.Kc4, then 1...b5+ is similar to the preceding variations. Only 1.Kd4!, avoiding Pawn checks, wins for White. If Black tries 1...b5, White can answer 2.a6, creating a shield similar to that seen in the previous diagram.. White first captures the Black Pawn and then forces the Black King away from the corner. In positions with two Bishops moving on the same color, the Rook's Pawn provides additional opportunities for the strong side. In the following diagram, White wins because the Black Bishop guards against the Pawn's advance from one side only.
White can force the Black Bishop away from the c1-h6 diagonal with 1.Bg7 Bd2 2.Bh6 Bb4 3.Be3. If Black establishes a guard on the long diagonal with 3...Bc3, then White continues 4.h6 Ba1 5.h7 Bb2 6.Bh6 and 7.Bg7. If Black tries to defend on the short diagonal with 3...Bf8, then 4.Bd4 Kh4 5.Be5 Kg4 6.Bf6 also wins. Black is forced to abandon the attack on the Pawn with 6...Kf4, after which White can offer to exchange Bishops with 7.Bg7 Ba3 8.h6. Now the Pawn promotes. The winning maneuver starting with 1.Bg7 was only effective because the Black Bishop could not switch to an attack behind the Pawn on other side (the imaginary j- and k-files!). If the White Pawn were a center Pawn, Black would have an easy defense switching the Bishop from one side to the other. If the Pawn is too far advanced, the maneuver in the previous position doesn't work. In the following diagram the Pawn has reached its seventh rank.
This is clearly drawn. If the Black Bishop stays on the a1-h8 diagonal, the White Bishop can never move to g7 without being captured. In major piece endgames, the Rook's Pawn favors the defense. Rook and Pawn are notoriously tricky and we won't delve into the complications here. In the following position, the distance of the Black King from the Pawn allows White to execute a winning maneuver.
White wins by transferring the Rook to the b-file with 1.Rh1 Ke7 2.Rh8 Kd6 3.Rb8. Black can make things difficult with 3...Ra2 4.Kb7 Rb2+ 5.Kc8 Rc2+ 6.Kd8 Rh2 threatening mate, but White has a nice trick starting with 7.Rb6+ Kc5 8.Rc6+. Now White wins with 8...Kb5 9.Rc8 Rh8+ 10.Kc7 Rh7+ 11.Kb8. Back to the diagram, if the Black King were any closer to the Pawn, the maneuver wouldn't work. With the Rook in front of the Pawn, the Black King must cling to a few safe squares. The following diagram shows a safe square.
The square h7 is also safe. If the King were on g6 (or h6), White could continue 1.Rg8+ (or 1.Rh8+), followed by 2.h8=Q. The following shows another unsafe square.
White wins with 1.Rh8 Rxa7 2.Rh7+, winning the Black Rook with a skewer. If the Black King is on a safe square, White can't win by approaching the Pawn with the King. Once the White King gets close to the Pawn, Black starts checking from behind and the King has no shelter. Positions with two Queens are generally drawn. As soon as the strong King tries to vacate the promotion square, it gets bombarded with checks from the enemy Queen. The weak side has to avoid positions like the following.
Here White wins with 1.Kb8. On any check from the Black Queen, White interposes its own Queen, cross-checking the Black King and forking both Black pieces, as in 1...Qd8+ 2.Qxc8+.
Most of the positions on this page are taken from Reuben Fine's Basic Chess Endings (BCE) and are numbered accordingly. Other positions are from Yuri Averbakh's Chess Endings : Essential Knowledge and Paul Keres' Practical Chess Endings.
Keres' book provides an unexpected example of how difficult these 'elementary' endgames can be. Consider the following position.
Keres (following Averbakh's example!) says that Black to move loses and gives 1...Bb3 2.a5 Bc4 3.Bb7 Bd3 4.Ba6 Bf5 5.Bb5 Bc8 6.Bc6 (zugzwang) 6...Kc4 7.Bb7. In fact, Black draws easily with 1...Bd5. If 2.a5, then 2...Bxc6 draws. If 2.Bxd5, then 2...Kxa4 is simple. If White withdraws the Bishop on the a4-d8 diagonal, Black repeats the sacrifice. Both Keres and Averbakh were world-class Soviet GMs and noted authors of several acclaimed endgame manuals, yet they overlooked this maneuver. The message to the rest of us is clear : beware the Rook's Pawn!
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