Exchanging a Fianchettoed Bishop
I would like to talk about the topic of exchanging off fianchettoed bishops, whether it is on b2, g2, g7 or b7. A fianchettoed bishop is useful both in defense, since it covers the king and on the other hand, without it there would be a complex of weak squares; and in attack, since it occupies a long diagonal. It is good to get rid of this bishop if it is a passive piece or when it would be easy to cover the weak squares it will leave behind. However, in many examples it is not favorable to exchange the bishop, since it is hard to cover the squares he defended with the other pieces. Let’s look at four examples where one side faced the exchange of the fianchettoed bishop.
In the first position, the kings are castled on different sides. White threatens Bg7, hg and Qh6. White has a better center and a target on d6, plus has a key square on d5. White’s attack is far ahead of black's; if he manages to trade dark-squared bishops then his position would be close to winning. Black’s dark-squared bishop is not only crucial to the defense of the king, but also located on a great open diagonal, while Rf8 has no prospects in the near future. Black decides correctly on what to do with Bg7.
Our next example features a typical English Opening vs. King’s Indian position. White gets space on the queenside and thanks to his strong bishop on g2 can put some pressure there. Black tries to defend the queenside, while playing for the kingside attack, starting with Nh5(Ne8) and f5. Also, as in the given example the light-squared bishops swap is possible, black should count on his attack, since he eliminates the main defender of the king. White has two options countering black’s plan: the first one is to play Re1 and on Bh3 just retreat with the bishop to h1. The other option is to allow the exchange but to take control of white squares immediately by regrouping (his pawns) e4-f3, then black has no hopes for attack, since f3-e4 holds the position very well. Lets see how these ideas were used in practice.
The next position is rather typical for the Queen's Gambit Declined. Black has an isolated pawn on d5 and due to the great pawn shield of white’s king and undeveloped black’s pieces no prospects for attack. Ideally, white would like to trade minor pieces to get into a major pieces endgame where the weakness on d5 would be greatly felt. It looks like Bb7 is a passive piece, but in reality it has a very important role of protecting light squares on the queenside as well as d5. By eliminating it, white creates targets for attack.
The next position is about equal. Black has weakened his kingside but white cannot really use it. Black wants to play in the center with c5 but this will activate Bb2, so he decides to trade it first and then to push c5. White might then have weak dark squares on the queenside.
One should be careful when facing the exchange of the fianchettoed bishop. In the second example it was a favorable operation, since by playing f3-e4 white maintained control of the light squares. On the other hand, the first example showed that black could not trade his bishop but had to save it at any price, since it was impossible to cover all the weak dark squares. The other two examples featured exchanges of bishops on the queenside, where the advantage the other side got was purely positional, as in weak squares and isolated pawns. Thus, the article looked at issues of exchanging fianchettoed bishops and how to either cover or exploit the weak squares complex that is there because of the missing bishop.
