Scotch Variation

The Scotch Variation, also called the Scotch Four Knights, uses White's extra tempo to strike at e5 at once rather than develop the king's bishop. The pawn exchange that usually follows opens the center for White's remaining pieces and gives a structure close to the Scotch Game. The position frequently arises from that opening via 3. d4 exd4 4. Nxd4 Nf6 5. Nc3. Choosing the Four Knights move order instead denies Black the Scotch replies 4...Bc5 and 4...Qh4, and keeps open the Belgrade Gambit, which the Scotch order cannot reach. Engines judge the position roughly balanced, and White scores somewhat better than Black in online play.

Black captures with 4...exd4 in the large majority of games, and 5. Nxd4 is the usual recapture. The main line, 5...Bb4 6. Nxc6 bxc6 7. Bd3, saddles Black with doubled c-pawns in exchange for central pawn mass and active pieces. The modern 5...Bc5 typically meets 6. Be3 Bb6 or the same exchanging scheme 6. Nxc6 bxc6 7. Bd3. The quieter 5...d6 can transpose to the Spanish Variation after 6. Bb5. The Schmid Defense, 5...Nxe4, uses a fork trick: after 6. Nxe4 Qe7 the pinned knight comes under fire, and Black follows with ...d5 to win back the piece.

The Belgrade Gambit, 4...exd4 5. Nd5, leaves the pawn on d4 and places the knight on a central square, inviting complications. It is far less common than 5. Nxd4. Black's choices include 5...Be7, the main line, the knight-trading 5...Nb4, 5...Nxd5, which leads to an early queen exchange, and the combative 5...Nxe4 6. Qe2 f5.

Among the alternatives to 4...exd4, the most frequent is 4...Bb4, pinning the c3 knight and leaving the e5 pawn to its fate. The Krause Variation, 5. Nxe5, takes the pawn at once, with 5...Qe7 known as the Leonhardt Defense. The Closed Variation, 5. d5, gains space and attacks the c6 knight; a common reply is 5...Ne7 6. Nxe5, while 5...Nd4 is the Oxford Gambit. The modest 4...d6 is also seen, though White has fared better against it than against the other main replies.