Colle System, Anti-Colle

The Anti-Colle, 1. d4 d5 2. Nf3 Nf6 3. e3 Bf5, develops the queen's bishop before ...e6 can lock it in, and places it on the b1-h7 diagonal where it watches e4 and opposes White's d3-bishop. The move targets the system itself. If White continues with the standard Bd3, Black can trade the light-squared bishops, removing the piece that was to support e3-e4 and the later kingside play, and leaving White with only the passive c1-bishop. Even so, 4. Bd3 remains the most frequent choice in practice, accepting the exchange for quick development. The principled 4. c4 abandons the Colle setup and heads into Slav-type positions, where the Bf5 development is standard. The quieter 4. Be2 keeps the bishop from being exchanged at the cost of some activity. Engines regard the position as roughly balanced and favor c4, Bd3 or Bd2. Results on Lichess are close, with White slightly ahead and draws uncommon.