Semi-Slav Defense, Marshall Gambit

The Marshall Gambit appears against Black’s pawn triangle on c6, d5, and e6. In algebraic notation, a pawn move uses its destination square, so 4.e4 means White advances the e2-pawn to e4 on the fourth move. That move immediately attacks d5 and offers the e4-pawn. A gambit is a voluntary investment of material, usually a pawn, in return for time, piece activity, or open lines. White wants to act before Black develops the g8-knight and consolidates the center.

After 4...dxe4 5.Nxe4 Bb4+, Black creates counterpressure with check. The main reply 6.Bd2 blocks the check and leads to concrete variations in which Black may try to keep extra material. White relies on rapid piece development, gains of time against Black's queen, and the chance to keep Black's king in the center.

What compensation means

Compensation is what a player receives for the material given up. In this gambit it may include a lead in development, the initiative, meaning the ability to create threats that force replies, and open lines for bishops and rooks. Compensation is not automatic. If White wastes time recovering every pawn, or Black exchanges queens and finishes development, the extra material may become a lasting advantage for Black.

The Marshall and the Noteboom Variation grow from the same triangle but from opposite choices. With 4.e4, White sacrifices to open the center. With 4.Nf3 dxc4, Black captures on the queenside and tries to support the pawn.