Minority attack

In my last article, I discussed a pawn formation a knight manuever which locked up the queenside.  Why would you want to do such a thing?  The answer, in that position, lied in black's plan of a minority attack.  A minority attack is a kind of plan based on pawn structure.  It is called a minority attack because black is attacking with less pawns on the side of the board then white.  The goal of the minority attack is to open lines, or create pawn weaknesses in white's position.  At all times it must be judged if those are really weaknesses, or if they are nothing to worry about for white.  Going back to the example from the last article, here is an example of a minority attack situation:

 Note that after the move indicated by the arrow, black will exchange pawns on c3.  White can choose to either recapture with a piece (the queen) or the pawn on b2.  If he chooses the pawn, then white ends up with a backwards pawn on c3 which can now be directly attacked.  If he chooses the queen, black can put pressure on the b-pawn on the open b-file.  Should white play b3, then black force a weakness by pushing his pawn to a4 and exchanging on b3.  

 What if white avoids the exchange on c3, by playing c4?  In our scenario, black could of course capture on d4, but what if in the specific position, this becomes an option?  In that case, black exchanges on c4, creating an isolated pawn on d4 for black to target.  Finally, if white prevents b4 altogether by playing a3, black will renew the threat by playing a6-a5, then again b4. 

 So we have a situation in which white will likely not be able to avoid ending up with a weakness.  This doesn't mean white will lose the game by any means - what it does mean is that black does not have to passively wait for white to build up on the other side of the board.  You can notice from the game from the previous article that white has more space on the kingside in effect - he can open up lines with f4-f5.  Black cannot move any of his kingside pawns without creating serious weaknesses.  For example, if black plays f5, he leaves a hole on e5 and gives himself a backwards pawn on e6.  

 With all of that in mind, white's move b4 starts to make a lot of sense.  It prevents black's counterplay idea.  It has the drawback of creating a backwards pawn on c3 , and a hole on c4.  The backwards pawn is not a factor because of white's Nb3-c5 maneuver, which we already discussed.  The hole on c4 is a factor, but it can be effectively covered by an exchange.  Note that while white can safely exchange on c4, black cannot safely exchange on c5, since when white replaces the piece with a pawn on c5, it becomes  a protected passed pawn.