Quiet Variation, Schallopp Defense

The Schallopp Defense, 4...Bf5, answers White's quiet 4. e3 by bringing the light-squared bishop out before ...e6 can shut it in, the standard aim of Slav setups. The bishop's departure leaves b7 less protected. However, the early probe 5. cxd5 cxd5 6. Qb3 is met by 6...Qc7. Because the knight on f6 already guards d5, the queen's double attack on b7 and d5 does not win a pawn. The exchange on d5 produces a symmetrical structure in which White's dark-squared bishop remains hemmed in behind the e3 pawn.

The most common and most testing reply is 5. Nc3, which develops and adds pressure to d5. After 5...e6 White can play 6. Nh4, hunting the bishop to obtain the bishop pair. Black's position stays sound, and the ...e5 break gives counterplay. Another option, 5. Bd3, offers a trade of light-squared bishops. Engines rate the position as close to equal, and the database results are split almost evenly between the two sides.