Balogh Variation

The Balogh Variation, 4. Bc4, develops the king's bishop with pressure on the knight on d5 instead of chasing it with c2-c4. This commits White to recapturing on e5 with the d-pawn. The obvious retreat 4...Nb6 gains time against the bishop, and it is by far the most common reply. Traps are a feature of the line. After 4...dxe5 5. dxe5, the natural 5...Nb6?? drops the queen to 6. Bxf7+. The earliest recorded game is Canal–Colle, Karlovy Vary 1929, which Black won. It is one of the more popular minor lines of the defense.

After 4...Nb6 5. Bb3, the older main line is 5...dxe5 6. Qh5. This zwischenzug threatens mate on f7 and frees the d-pawn from the pin on the d-file, so that after 6...e6 7. dxe5 White can recapture. Black can also play 5...Bf5, when White has the disruptive pawn sacrifice 6. e6. Both lines give White attacking chances, so some authors favor 5...d5 followed by ...e6, reaching a French-like structure. Engines rate the position as level, and Black scores slightly better in practice.