Advance Variation, Prins Attack

The Prins Attack, 4. b4, is an uncommon fourth move in the Advance Caro-Kann. Instead of developing or chasing the f5-bishop, White grabs queenside space and covers c5, aiming to hinder Black's standard ...c5 break against d4. Black nearly always answers 4...e6, completing the usual setup, while 4...a5, striking at the advanced b-pawn, is a rarer option. Black scores well in the database, and the engine rates the position as roughly balanced.