Chess Strategy/Pawn structure

The soul of the game
In every chess primer, there seems to be one bit of wisdom that is quoted over and over again. This is the quote by the French master Philidor, who said, two hundred and fifty years ago, "Pawns are the soul of chess." But what does it mean? GM Andrew Soltis expresses everyone's feelings in his excellent book, Pawn Structure Chess : "There always used to be one bit of advice that was always fobbed off by the authors. 'As Andre Philidor once said, the pawns are the soul of the game.' 'Great,' I'd say to myself every time I read this. 'A Frenchman who's been dead for two hundred years is saying I shouldn't worry about losing my queen or being checkmated. I should be worried about pawns.'"

He then goes on to explain why pawns are so important in chess strategy. The answer is simple. Pawns are very immobile, almost motionless for the majority of the game. But it is this immobility that gives the position its character. The pawn structure lays out the terrain for the coming battle, providing lines for your army. Pawn Structure Chess is more about characteristic, specific structures that can arise from certain openings and the basic plans for each side. However, we are not going to go so in-depth in this book.

"Weak" pawns
Often the amateur will cringe in horror when noticing "weak" pawns. They notice the doubled pawns on c3 and c2 and immediately favor the other side. This is not right! Chess is a game of dynamics. While "textbook weak", "weak" pawns may not really be weak and in fact may offer dynamic chances for one side or another! To illustrate this point, let's look at a generalized example, Hammie—Silman, San Francisco 1975. 1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 g6 The popular Accelerated Dragon. 5.Nc3 Bg7 6.Be3 Nf6 7.Bc4 Qa5 8.O-O O-O 9.Nb3 Qc7 10.f4 d6 11.Be2 b6 12.Bf3 Bb7 13.Rf2 (diagram)

Black is cramped. He would like to get his natural play on the queenside (since that is usually where Black plays in the Sicilian), but it seems that White's knights are hampering him. So, what does he play? 13...Na5! Black is willing to accept doubled pawns in exchange for dynamic play on the queenside. In this case, the pawns cannot be easily attacked, so what's the big deal? However, the challenging reader may ask, "What's so great about the doubled, isolated pawns? Did they play a part in the fight?" Silman gives us an instructive lesson. 14.Nxa5 bxa5 15.Bd4 Nd7 16.Nd5 Bxd5 17.exd5 Bxd4 18.Qxd4 Qc5! Black wishes to trade queens, because then White will be deprived of any counterplay on the kingside. 19.Rd1 Rab8 20.c4 Rb7! Black eventually won. Now suppose, for instructional purposes, the game went on: 21.Qxc5 Nxc5 22.b3 Rb4 23.Rb2 Rab8 24.Rab1 Kf8 25.g3. The sharp reader might be saying that the doubled pawns did not actually give Black the advantage; it was the open b-file. He would be proved wrong after '''25...a4! 26.Bd1 a3!''' The typical idea is to take on b3 and advance the other pawn. However, another equally strong idea is available in the position. 27.Rc2 a5 28.Rc3 a4 Now we see the point—after ...axb3 axb3, the "weak" pawn on a3 has been turned into a powerful passed pawn.

The different types of structure
These structures have dynamism to them; they can be classified as either good or bad.

Doubled pawns
Doubled pawns are most commonly seen on c2-c3, f2-f3, c6-c7, or f7-f6. This occurs when a bishop exchanges itself for a knight on one of those natural developing squares. Doubled pawns are not always weak. However, it is true that the flexibility of a pair of pawns is significantly decreased if they are doubled. Let's look at a line in the Nimzo-Indian Defense: 1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.a3 Bxc3+ 5.bxc3 White has doubled pawns now. The pawn on c3 is safe from harm, but the pawn on c4 is a target for Black's pieces. Or, in a famous game from their 1972 World Championship match, between Spassky and Fischer, the doubled pawns ensured that White's queenside play was shut down and Black could freely proceed on the kingside. He eventually won.

The isolani
When we talk about an isolated pawn we are usually speaking of a d-pawn. This IQP (Isolated Queen's Pawn) formation usually occurs in the Queen's Gambit. The main negative of an isolated pawn is that it itself is weak and has no neighboring pawns to guard it. In addition, the square in front of an isolated pawn becomes an excellent outpost for a knight, since there are no neighboring pawns to kick out the rude knight.

However, isolated pawns have their pluses, too. An isolated queen pawn, especially, has additional pluses. Isolated queen pawns stake out a slight central space advantage, give its owner play down the open c- and e-files, and provide chances for a dynamic attack. The sacrifice on d5 of a pawn on d4 is the same as converting potential energy into kinetic energy. Let's look at an example.

This is Keene—Miles, Hastings 1975. White has an isolated queen pawn. However, Black has no really great way to make use of this fact. 11.Bg5 Note that Black cannot take on d4 because of 11...Nxd4 12.Nxd4 Qxd4 13.Bxh7+ winning the queen. 11...Nb4?! Black should have taken time to develop his bishop. 12.Bb1 b6 13.Ne5 The e5-outpost is another benefit that is derived from the isolated d-pawn. 13...Bb7 14.Re3! White plays for mate. He must play actively, lest the pawn on d4 becomes a problem for him. 14...g6 15.Rg3 Rc8? Black does not sense the danger. Instead, he plays a move which wastes time. According to Keene, Black should have sacrificed the Exchange with 15...Nc6 16.Bh6 Qxd4! 17.Qxd4 Nxd4 18.Bxf8 Kxf8, with only a slight advantage to White. 16.Bh6 Re8 17.a3 Nc6 Now a series of sacrifices tear apart the Black king. '''18.Nxg6! hxg6 19.Bxg6! fxg6 20.Qb1! Ne5 21.dxe5 Ne4 22.Nxe4 Kh7 23.Nf6+ Kh8 24.Bg7+! Kxg7 25.Qxg6+''' with mate to follow.

As you can see, this was not a really great example of the "weakness" of the isolated queen pawn. Instead, it was a perfect illustration of the active piece play that such an isolani gives its opponent.

Other isolated pawns
Isolated pawns are not always on d4. Sometimes Black has them on d6, which makes the weakness look even bigger than usual because now White has an outpost on d5, not d4—which is even further advanced then the post given to White in a normal IQP position. However, these pawns have their pluses, too. d5 is more easily guarded by Black pieces, so a White knight will find it hard to occupy without being exchanged. For example, d5 in the Najdorf Sicilian is usually guarded by a knight on f6, a bishop on e6, and occasionally, a knight on b6. A d6-pawn also covers the important e5- and c5-squares.

Hanging pawns and the isolated pawn couple
A structure that can easily derive from the IQP is what Nimzowitsch dubbed "the isolated pawn couple", with pawns on c3 and d4. A formation like this gives the second player good outposts on the squares in front of the isolated pawn couple (for an example, refer back to Rubinstein—Salwe, Łódź 1908). However, this is not the whole story. These pawns have the potential to become "hanging pawns", on c4 and d4. In addition, the pawn on d4 is no longer weak with the c-pawn there, and White still gets his kingside chances as in the IQP.

Hanging pawns on c4 and d4 are very hard to evaluate. Nimzowitsch once said that the hanging pawns must be advanced, but most players advance it either too early or too late, that the human consciousness is not used to the idea of "being in the air". In addition, the advance of either pawn leaves weak squares in its wake. Either way, the hanging pawns on c4 and d4 gain space, but are subject to pummeling down the open c- and d-files. Let's look at an example.

Black is playing against the hanging pawns, which take away the knights' posts on c5, d5, and e5. If he could get one to advance he would have nice outposts for his knights. Therefore, he plays 16...e5! This forces the d-pawn to leave. 17.Be3 exd4 18.Bxd4 Ne5 19.Qf5 Nxd3 Now Black eliminates White's bishop pair advantage. 20.Qxd3 Rfd8 21.Qc3 Ne4 Heading for c5. It's clear that Black has taken the upper hand. 22.Qb2 Nc5 23.Qc3 Ne6 Black's nimble knight dominates the clearly worse bishop on d4. 24.Be3 Rd6 25.Rc2 Qd7 26.Qb4 Rd3 27.a4 It may seem as if White has made progress. He is about to play a4-a5 when Black's queenside is weak. However, Black gets a strong attack on White's king by marching forward his f-pawn. The knight on e6 is also useful in this respect, guarding f4. '''27...f5 28.g3 f4 29.gxf4 Nd4! 30.Bxd4 Qg4+ 31.Kh1 Qf3+ 32.Kg1 Rc6!''' Lifting the rook to assist in the devastation. 33.f5 Rxd4 34.h3 Rg4+!, and White had to resign (35.hxg4 Qxg4+ 36.Kh2 Rh6#, checkmate).

Note how masterfully Black played against the hanging pawns. First he isolated one, then eliminated the advantage of two bishops. With White advancing on the queenside, Black was able to launch a successful attack on a weakened White king while White's forces were distracted on the queenside. Eventually Black converted his structural and minor piece advantage into victory.

Backward pawns
A backward pawn is a pawn whose neighbors have advanced ahead of it and cannot advance. In the past, backward pawns were always looked down upon as weaknesses. However, today they are considered an intrinsic part of modern opening theory. For example, in the 6.Be2 variation of the Najdorf Sicilian, Black often accepts a backward pawn on d6 after the moves 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Be2 e5! Black voluntarily takes a backward pawn on d6. Although the knight will move, Black's pawn on e5 controls d4 and f4 and also blockades e4, giving Black pressure there. In addition, Black is also threatening to play the thematic ...d6-d5 at any moment in the game, giving White something to worry about. The move ...e7-e5 also kicks back the White knight to a less enticing square.

However, backward pawns can be weak. Specifically, although the pawn itself may be easily defensible, the square in front of it is a tasty outpost for the enemy pieces, especially a knight. Also, due to its inability to advance, the backward pawn is an easy target for heavy pieces. At right is the game Unzicker—Taimanov, Stockholm 1952.

White has just played 13.b3?, a move which weakens the knight on c3 and thus, the pawn on e4. This is the kind of pressure I was talking about earlier—if Black can line up his queen and bishop to target e4, White will be forced to defend passively to preserve material equality. Black also has a backward pawn. However, it can hardly be considered a weakness, since it is securely defended by a bishop and queen, while White cannot muster enough force to take the pawn. Nor can he move his knight to d5, since then Black would take it, retreat his knight to b8, advance the kingside pawns, redeploy his knight to f6, and have good kingside chances due to his space advantage in that area and active bishop pointing in that direction. So in this position Black played 13...Rc8 14.Bb2 Rc7! A multi-purpose move. The first purpose is to gang up on the c3-knight with ...Rf8-c8, after Black moves his queen to a8 to target the e4-pawn. 15.Nb1 Qa8 16.Nbd2 Nd8! Black redirects his knight to e6, where it can choose from c5 and f4 as squares. In addition, Black has opened the long, light diagonal for his queen-and-bishop battery, and opened the c-file for his rooks. 17.Bd3 Ne6 18.Rc1 Rfc8 19.Nh2 Nd7 20.Nhf1 Ndc5 21.Ng3 g6 White was aiming for f5, where he would exert pressure on d6 and its only defender, the bishop on e7. 22.Ne2 Bg5! After 22...Nxe4 23.Nxe4 Bxe4 24.Bxe4 Qxe4 25.Nc3 White has lost a pawn, but he has gained use of d5 and e4 as outposts. Black's move is stronger, keeping White tied down. 23.Nc3 Nd4 24.Ncb1 d5! Breaking open the center and exposing White's confused pieces. All of Black's pieces are active. 25.exd5 Nxd3 26.cxd3 Rxc1 27.Bxc1 Bxd5 28.f3 Rc2 29.a4 If ''29.Rxe5? Qc6 30.Re1 Rxc1 31.Rxc1 Qxc1 32.Qxc1 Ne2+'' and Black wins. 29...b4 30.Kh1 Qc6 and White resigned! He has no good way to prevent ...Nxb3.

So the backward pawn was not really "bad", but what good did it do for Black's position? For one thing, it protected e5 for a while. Second, without the backward pawn on d6, Black would never have been able to force in the line-opening 24...d5!. The result of the game depended on this advance—without it, Black could not have broken through. The reason this advance was so effective is that White's pieces were confused and passive. There was no way to get to them except through the center. After the center was open, White's ranks were in chaos and they were subject to attack by Black's active, well-coordinated army. As any general knows, this is a recipe for disaster.

Passed pawns
Most players think passed pawns are always good. In the endgame, this is certainly true. However, this is sometimes not true, especially in the middlegame. Passed pawns can get in the way of their own pieces and become a bottleneck. This is especially true when a knight blockades it. Knights are excellent blockading pieces because, although relegated to the role of defensive barricade, their ability to jump over pieces allows them to exert pressure on the squares behind the pawn. The American World Champion, Bobby Fischer, played a famous game against the then-World Champion, Boris Spassky, in the World Championship match in 1972, with a passed pawn.

Most masters of the early twentieth century would here conclude that White has a large advantage. After all, he has more central space, a protected passed pawn on d5, two bishops, and a weak pawn on b6 to target! The opposite is in fact true: Black has the advantage because he has a knight versus a bishop in a closed position; the pawn on b6 is easily defended, White has weak pawns on c4, c3, and a4, and the d-pawn only serves to block White's actions on the d-file. As a result, White has no plan. 18.Rb2 Rb8 19.Rbf2 Spassky correctly transfers the rooks to the kingside, which is where all the action is taking place. 19...Qe7 20.Bc2 g5 21.Bd2 Notice how White is playing planlessly, due to the passivity of his two bishops. However, Black has a clear plan of playing his knight to f4 while exchanging White's best pieces, the rooks. Then he will target the weak White pawns. Thus, he plays: 21...Qe8 22.Be1 Qg6 23.Qd3 Nh5! Trading off the rooks and swinging the knight into f4. 24.Rxf8+ Rxf8 25.Rxf8+ Kxf8 26.Bd1 Nf4 The difference between minor pieces is clear. Here Spassky blundered with 27.Qc2 and promptly resigned after 27...Bxa4!, which wins two pawns and crashes through. However, it is more instructive to see what would have happened had Spassky played 27.Qb1. '''27.Qb1 Qf6 28.g3 Ng6 29.Bf2 Ne7 30.Bc2 31. Nc8 31.Qd1 Ke7 32.Be3 Kd8 33.Kg2 Nd6 34.Qe2 Qf7!''' There is little that White could do about Black reaching this setup. Black's knight sits unassailably on d6. Were the pawn on d5 not there, White could play Qd2 and chase it away. However, the pawn is there, and it sits on its outpost attacking both c4 and e4. This shows the disadvantage of White's passed pawn—it blocks the actions of his pieces. Black's next move will be 35...Qe8, winning a pawn. So White probably would have lost the game in any case.