...One Lowly Pawn

OBIT
OBIT
Sep 5, 2009, 12:00 AM |
22 | Endgames

In this article, we are going to look at positions where you are down to your last pawn, while your opponent still has a piece left. Facing a knight, bishop, rook, or even a queen, what are some of the positions where the lowly pawn can still lead you to victory? As these positions will show, even when down to your king and a single pawn, there are wins that require some surprisingly complex maneuvering.

Let's start with pawn vs queen. Now, it should come as no surprise that, for you to win, not only does your pawn have to be ready to promote, it better be promoting with check. For a trivial example of this, start by placing a White pawn on b6, the White king on c7, the Black king on a8, and then fill the rest of the board with as many Black pieces as you like, so long as they have no influence on the squares b6, b7, b8, or c7. The obvious mate is 1. b7+ Ka7 2. b8=Q+ Ka6 3. Qb6#.

Of course, for our pawn vs queen winning example, we’d like a position where the winning line is more complex than that. Basically, we need a position where White can reach a won K+Q vs K+Q endgame, and yes, there are some won K+Q vs K+Q endings where the win isn't just some quick skewer check to capture the queen. So, let’s find one… ah, this one will do quite nicely:

For anyone who thinks this position looks unnatural, with the Black queen sitting in the corner, well, it is easy to imagine this position arising at the end of a pawn race, where Black has just played ...h1=Q. Now White has a nice winning maneuver that exploits the bad placement of the queen: 1. a8=Q+ Kh2 (1...Kg1 2. Qa1+ returns to the main lines after 2...Kg2 3. Qb2+ or 2...Kh2 Qe5+) 2. Qh8+ Kg2 (if Black tries to hold the draw by avoiding ...Kg2, White makes progress by checking on the diagonals, i.e. 2...Kg1 3. Qd4+ Kh2 4. Qe5+ Kg1 5. Qe3+, and now 5...Kh2?? allows 6. Qg3#) 3. Qb2+ Kf1 (3...Kg1 allows White to reach the key position immediately with 4. Kg3!, when White's mating threats cannot be prevented. In the moves that follow, White is trying to force this position, Black is trying to prevent it, and White ultimately gets his way.) 4. Qc1+ Kg2 5. Qd2+ Kf1 6. Qd1+ Kg2 7. Qe2+ Kg1 (now forced) 8. Kg3! and now White only has to avoid a last cheapo: 8...Qf3+!? 9. Kxf3 (not 9. Qxf3?? stalemate)

Moving on to pawn vs rook, we may as well start with what is undoubtedly the most renowned endgame position in all of chess literature, the "Saavedra Position." (Imagine, a position so famous, it gets its own name!) I've presented this position below as a puzzle, although I realize you readers who already know it will complete the puzzle in... oh, I see you're done already.

White wins by 1. c7 Rd6+ 2. Kb5! (the only move - 2. Kb7? allows 2...Rd7, while 2. Kc5? allows 2...Rd1!, when c8=Q is not possible because of Rc1+. The White king now runs down the b file to evade the ...Rd1 drawing move:) Rd5+ 3. Kb4 Rd4+ 4. Kb3 (4. Kc3 Rd1 5. Kc2 is also fine, transposing to the main line after 5...Rd4!) Rd3+ 5. Kc2. So, it appears White has achieved his objective and will queen his pawn now, but Black has one last surprise: 5...Rd4! Now if 6. c8=Q Rc4+! 7. Qxc4 stalemate! Also, 6. Kc3 Rd1 or 6. Kb3 Rd3+ just repeats an earlier position. There is an amazing winning move, however (and yes, this is why the position gets its own name): 6. c8=R! Underpromotion, incredible! Black's only move to stop Ra8# is 6...Ra4, but then 7. Kb3! wins the rook or mates.

Yep, there is no denying a lot goes on in this simple position. Studying the position a little more, you'll note the king's run down the b-file to escape the rook's checks would be needed in many similar positions. For example, change the position by putting the Black king on f7 or g7 instead of a1, and the first five moves of the win do not change - the only difference is that last ditch stalemate try is no longer available. In fact, there are won positions for pawn vs rook in which the main line involves running down one file, then running up another file. (This may not be quite as interesting as an underpromotion, but it does mean the main line is longer.) For an example of this, see the next position:

After 1. c7 Rf6+ 2. Kd5! (as with the Saavedra position, the king must run down the file to escape the checks. Here, 2. Kd7? is met by 2...Rf1! 3. c8=Q Rd1+ 4. Kc7 Rc1+, trading down to a draw.) Rf5+ 3. Kd4 Rf4+ 4. Kd3 (or 4. Kc3 Rf1 5. Kc2) Rf3+ 5. Kc2. Phase 1, running down the d-file is complete. Now the king runs back up on the b-file: 5...Rf2+ 6. Kb3 Rf3+ 7. Kb4 Rf4+ 8. Kb5 Rf5+ 9. Kb6 Rf6+ 10. Kb7, finally escaping the checks and allowing the pawn to promote next move. Now all you have to do is win that brutally difficult K+Q vs K+R endgame. (Ah, but don't worry. Against a computer programmed to pick its moves off a tablebase, you'd stand little chance of finding your way through this labyrinthine ending, but against another human there’s a good chance your opponent will make a mistake that lets you trap his rook.) For one final point, you may notice this maneuver would not have worked with a b-pawn; for example, slide every piece one file to the left, and the final position is still drawn after 10. Ka7 Rf1 11. b8=Q Ra1+.

Let’s move on to pawn vs bishop. Your instincts might be to think that, with the long range potential of the bishop, there aren't many winning positions and even fewer wins that require several moves. And, OK, in this case you happen to be correct – this is actually a pretty arid endgame for interesting ideas. The best I can offer is the following position, where it takes the pawn six moves to promote. Six moves may sound like a fairly long combination, but, if you want to try this position as a puzzle, I'll bet you find all the moves:

After 1. a6 Ba2 2. Ke4 (stopping ...Bd5) Be6 3. a7 Bh3 (one last try, hoping to sneak in the back door) 4. Kf3, and Black has one last spite check before the pawn's coronation. As I said, no sweat.

Lastly, we get to pawn vs knight. Due to the knight's inability to attack from long range, you might expect this to be the most complex of the four endings, and again your instincts would be correct. In fact, there are even won positions (quite a few of them, in fact) where the pawn is still on its original square – the pawn travels the length of the board to win. The following position is an example, where it takes a remarkable 13 moves for the pawn to reach the eighth rank:

After 1. a4 Ng5 2. Kd6! (the king has to take an active role, else the knight is able to get in front of the pawn) Nf3 (if 2...Ne4+ 3. Kc6, and the White king is ideally placed to escort the pawn through. From here I'll just give the main line:) 3. Kd5! Ne1 4. a5 Nd3 5. Kc4! Ne5+ 6. Kb5! Nf7 7. Kc6 Ne5+ 8. Kc7 Nc4 9. a6 Na3 10. Kc6 Nc4 11. a7 and the pawn is through.

In this ending, subtle changes to the placement of the pieces can have a dramatic impact on the outcome. For example, let’s change the above position by putting the Black king on h1 instead of h4:

With the Black king even further from the action, you might think White’s win is that much easier, but in fact now Black can draw. After 1. a4 Ng5 2. Kd6 Nf3 3. Kd5, the only move to draw, amazingly, is 3…Nh4!!, which seems to be moving the knight in the wrong direction. (Note, however, that this explains why the Black king is better off on h1 rather than h4 – the knight needs this square.) From here, a possible continuation is 4. a5 Nf5! 5. Kc6 Nd4+ 6. Kb6 Nf5! 7. Kc6 Nd4+ 8. Kb6 Nf5 9. a6 Nd6 10. a7 Nc8+ and draws.

I’ll close this article with one more winning pawn vs knight example, this time with a b-pawn, which I will present as a puzzle. In this position, you’ll note the knight does not appear to be too badly placed, but with precise play White still gets the pawn through. It’s tough, but try it and see how many moves you can get:

To win, first the knight has to be chased away: 1. Kd3!! Kg5 2. Kc3! Nc1. From here, the plan is more straightforward – just prevent the knight from getting in front of the pawn. 3. b5 Ne2 4. Kc4 Nf4 5. b6 Ng6 6. Kd5 Ne7+ 7. Kc5 Kf6 8. b7 and wins.

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