"In the middle of the game the main thing is the coordinated activities of the Pieces, it is just here that the weak side of the majority of players lies. Many try to attack by one Piece at one point, by another one, at another point, without concentrating their efforts, and then ask with astonishment, where did they make a mistake.
You should coordinate the activities of your forces, this is the main principle going through the whole game."

Jose Raul Capablanca, Champion of the World