Queen's Gambit Declined - Harrwitz attack
1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Bf4
White advances the queen's pawn to d4. Black moves the queen's pawn to d5. White plays the c-pawn to c4.
Black advances the king's pawn to e6. White develops the knight to c3. Black develops the knight to f6.
White develops the dark-squared bishop to f4.