Welcome to the first edition of Endgame Corner, where we will be taking a deep dive into a different fundamental theoretical endgame each week. The idea is to accumulate a steady base of knowledge across a wide variety of endgames, with two specific goals:
- For each endgame, to know the evaluation of certain key positions.
- To know which fortresses the defending side can construct, or how to break down setups which may seem like impenetrable fortresses.
This is a key part of any strong player's toolkit, as frequently in a complex endgame we face moments where we can force a simplification to a theoretical position we may have studied. If we have exact knowledge of which theoretical positions we should be aiming for and how to win or draw them, it makes playing the more complex endgames that much easier.
We will begin with the most basic of positions, and will progressively be able to graduate to more complex positions once we know the basic ones.
For this week, our topic is: rook versus bishop (no pawns).
This should already be well-known to more experienced players but it is always good to practice the cases where the defending side goes wrong - you can definitely set up small tricks in a practical game.
 |
| Position 1 (black to move) |
In the worst-case scenario, if the defender's king is cut off to the back rank, the position is drawn as long as defender's king is in the "safe corner" of the opposite color as the bishop. In this situation, 1. ... Rh2 2.Bf5 (white can move the bishop to any safe square along the b1-h7 diagonal) 2. ... Rh1+ 3.Bb1= and any rook move on the first rank would be stalemate.
There is also no way for black to create a zugzwang here, as the bishop will always have several safe squares to move to along the b1-h7 diagonal.
If black maneuvers the rook to give a check on a2, white will slide the king to b1, and any rook move back along the 2nd rank will allow white to put the king back on a1. For example: 1. ... Rh2 2.Bf5 Ra2+ 3.Kb1 Rf2 4.Bh7 Kb3 (if black keeps attacking the bishop it will just keep running away, staying on the b1-h7 diagonal, and checking on the first rank allows Kc2, escaping) 5.Ka1= back to the safe corner.
Finally, black could try to put the king on b3 and then give check with the rook along the a-file, forcing white's king to b1, and then try switch the rook back to "pin" the bishop to checkmate along the first rank. But even if black succeeds in making this "pin", white always has Bc2+ (an important resource) to escape. For example, from Position 1: 1. ... Kb3 2.Bf5 (white need not even play Bd5+) 2. ... Rf8 3.Bh7!? (just to illustrate even the "worst"-case scenario) 3. ... Ra8+ 4.Kb1 Rh8 5.Bc2+ Kc3 (5. ... Ka3 6.Ka1= is familiar to us) 6.Bf5= (or anywhere safe along the b1-h7 diagonal) and black is no longer threatening checkmate.
The main "trap" to be careful of here (and why you should always play it out in a real game, to test your opponent) is the following, still from Position 1: 1. ... Kb3 2.Bf5 (following our rule, just keep the bishop on this diagonal) 2. ... Ra8+ 3.Kb1 Rf8 and if white tries to be "clever" with 4.Bd3?? (instead 4.Bc2+ Kc3 5.Be4= holds) then 4. ... Rf2! (D) leads to an instructive winning domination position for black (although it is not immediately obvious that it is winning):
 |
| Position 2 (white to move) |
White would need to be giving a check along the a2-g8 diagonal to save the game, but because of the unfortunate placement of the bishop on d3, this is not possible (although we wouldn't even be getting to this situation had we followed the simple rule to give check on c2 after 3. ... Rf8). After 5.Ka1 Ra2+ 6.Kb1 Rd2 -+ black wins the bishop, and the threat is anyway to play Rf2-d2. In case of 5.Kc1 Kc3! white is forced into 6.Bb5 (6.Ba6 Ra2 -+) when now 6. ... Rf5! forces back 7.Be2, and finally 7. ... Rg5! (D) dominates the bishop, winning it:
 |
| Position 3 (white to move) |
This position really makes you appreciate why the rook is so much stronger than the bishop in an endgame. White loses the bishop after any of 8.Kb1 Rg1+ 9.Ka2 Rg2; or 8.Kd1 Rg1+; or 8.Bd1 Rg1; or 8.Ba6 Ra5.
So, going back to Position 2, the most resilient defense is to try and hide the bishop with something like 5.Ba6, but then 5. ... Rd2! 6.Kc1 (forced) 6. ... Rd4! (D) is another key position:
 |
| Position 4 (white to move) |
On 7.Be2 or 7.Bf1, black is able to force the domination seen in Position 3 (it is a good exercise to practice it so that you know how to execute it properly). For example: 7.Bf1 Kc3! first setting up opposition so that there will be mate threats on the back rank 8.Be2 Rd2! 9.Bb5 Rd6! 10.Bf1 Rf6 11.Bb5 Rf5! 12.Be2 Rg5 -+. The try 7.Be2 Kc3! 8.Kb1!? is met with 8. ... Rb4+! 9.Kc1 (9.Ka1 Kc2! mates) 9. ... Rb2! and black eventually will achieve the Position 3 domination.
So from Position 4, more resilient is 7.Bb7 (7.Bb5 is similar), when black wins by setting up a second type of domination: 7. ... Kc3! again first setting up opposition for mate threats - the bishop is now confined to the b, c, or d-files as otherwise black can fork/pin it to checkmate 8.Bc6 (black is making good use of the temporary fact that white's king could not have escaped the mating net with 8.Kb1 because of the fork on b4) 8. ... Rd6 9.Bb5 Rd5 10.Bc6 Rc5 11.Bd7 Rc7 (D)
 |
| Position 5 (white to move) |
The bishop is trapped. Either it goes off the b, c, or d-files and is pinned/forked to checkmate, or it is captured after 12.Bb5 Kb4+.
This second type of domination seen in Position 5 will help you appreciate why the endgame is lost if the defender's king is in the "dangerous corner" - the same color as the bishop:
 |
| Position 6 (black to move) |
In this situation, if black ever checks on the back rank, blocking with the bishop on f1 will not lead to stalemate after a waiting move by the rook, but instead force Kh1 Rxf1#. But if black tries to go for mate directly with 1. ... Ra2? then 2.Kf1= and white will escape (2. ... Kf3 3.Ke1 Ke3 4.Kd1=). Instead, black wins by setting up a similar kind of domination to the one seen in Position 5 (another good exercise to practice, so that you know you can execute it properly): 1. ... Rf8! (other options also win; this is just the fastest) 2.Bh7 Rh8 3.Bg6 Rh6 4.Bf5 Rc6! and white is out of defenses, as the desired 5.Kf1 allows Rf6! pinning and winning the bishop.
Last but not least - white would still be OK if the king was cut off only "near" the dangerous corner, without actually being trapped in it yet. For example:
 |
| Position 7 (white to move) |
We should be careful, and notice that black is planning 1. ... Rf3!, which would be attacking the bishop and simultaneously threatening ...Rf2+ followed by Kg3, trapping our king in the dangerous corner. For example, black to move here wins after 1. ... Rf3! 2.Be4 Rf2+ 3.Bg2 (3.Kg1 Kg3 and black will win as in Position 6) 3. ... Re2 4.Kg1 Kg3 -+
But as long as the bishop stays off the f-file, white is OK. We will hold the draw after 1.Bc8 Rc3 (in a practical game, black could also try to be tricky with 1. ... Rg8 hoping for 2.Bf5?? Rf8! followed by Rf2+ and Kg3) 2.Bb7 Rc2+ 3.Kg1 Kg3 and importantly, black does not yet have the rook on f2, so white escapes with 4.Kf1!=
