English Opening, Carls-Bremen System

The Carls-Bremen System appears within the King's English when White plays c4, develops the knight to c3, and prepares g3, while Black places a pawn on e5 and a knight on f6. The move g3 clears a route for the f1-bishop to reach g2.

This bishop development is called a fianchetto: the g-pawn moves one square and the bishop takes the long diagonal from g2. From there it helps control central light squares, especially d5. White has not moved the g1-knight yet, so it may go to f3 for natural development or to e2 if White wants the f-pawn to remain free.

The system's main value is flexibility. With Nf3 it can approach the Four Knights Variation; with d3, e4, and Nge2 it can become a Botvinnik formation. Therefore g3 does not determine the whole plan. Later choices for the g1-knight and the d- and e-pawns shape the kind of position that follows the opening.