Wednesday, November 18, 2015

Basic Rook vs Minor Piece Endgames: Part 1

And you thought I was finished with rook endgames! Like I once said, the breadth of rook endgame positions is so vast that many of us are far from mastering them.

Since we have managed to cover most of the basics of rook-pawn endgames (see database), I shall extend the discussion to basic rook vs minor piece positions. For today, we will be looking at a pure rook vs bishop endgame.

Let the showdown begin (Image from Dreamstime)

Many players, when encountered with this endgame, simply assume it is a draw and forget about it. They are right that it is usually a draw; but when faced with strong opposition, chances are they botch the defense and end up losing the game.

There is a simple rule to this. To defend successfully, the side with the bishop must stick his king in the opposite-coloured corner of the bishop.

Sounds weird? I will save on wordy explanation by throwing in a counter-example: When the defender has his king in the corner with the same coloured square as his bishop:

Position 1: White to move and win

Here, Black's bishop is dark-squared, and his king has been chased to a dark-squared corner (similar colour to the bishop). Now White can use a checkmate threat to win the bishop:

1. Rf1

Buying time for White to bring his rook into a suitable mating position. The immediate 1. Rc4? allows Black to escape with Kf8

1... Bh2

Or 1... Bd4 2. Rd1 Bb6 3. Rb1 Bc7 4. Rc1 Bd8 5. Rc8 winning with the same concept as the main line.

2. Rf2 Bg1
3. Rg2

Now Black's bishop is no longer safe on g2 and h2.

3... Bd4
4. Rd2!

A skewer: White is eyeing the d8 square where he can deliver mate.

4... Bb6

Black tries to defend.

5. Rb2 Bc7
6. Rc2

Now Black can no longer protect the light-coloured square c8.

6... Bd6

Or 6... Bd8 7. Rc8 winning.

7. Rc8+ Bf8

Blocking the check, but White simply plays a deadly waiting move:

8. Ra8!

The bishop is pinned, and Black is forced to step away.

8... Kh8
9. Rxf8#
1-0

...

So far so good... we know how the attacker can get a win by combining a mating threat with a pin. But that doesn't answer the question of why the defender can draw if he brings his king to the opposite-coloured corner?

What better explanation than another example:

Position 2: Either side to move draws

Now the defender has stuck his king in the right coloured corner. As usual White tries to chase out the bishop and employ his checkmate threat:

1. Rc2 Be5
2. Re2

Same old skewer, aiming for checkmate on e8.

2... Bf4!

Black keeps his bishop on the h2-b8 diagonal. You will see why.

3. Re8+

Of course 3. Re7 Bg3 4. Rf7 Be5 makes no progress.

3... Bb8
4. Kc6

The only way to continue if White wants to win.Now White cannot play the waiting move 4. Rf8?? because it'll be stalemate. Here, the Black king has no free square to go to. Take note of the difference between this and our previous example!


4... Ka7
5. Re7+ Ka8
1/2-1/2

But Black simply tucks his king back onto a8 and it's back to square one.

...

So here we have, a basic summary of how to play a pure rook vs bishop endgame:

  • As the defender, the safest way to draw will be to bring your king and bishop over to the corner with opposite-coloured square to the bishop. There, you can put your bishop on the correct diagonal to interpose any rook checks safely. The stalemate threat will save you.
  • As the attacker, your winning chances lie in luring the opponent's king to the same coloured corner square as the bishop, where you can use a checkmate threat to pin the bishop and win it.

In Part 2, we will move on to Rook vs Knight endgames.

Sources:
http://www.dreamstime.com/royalty-free-stock-photo-rook-bishop-chessboard-image27059045
"21 Days to Supercharge your Chess - Endgame Package" by Yury Markushin

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