Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nf6/3. Nxe5/3...Nc6/4. Nxc6/4...dxc6/5. d3/5...Bc5

Stafford gambit with 5. d3 C42 Stafford gambit 5...Bc5 Black develops their bishop to pressure White's vulnerable f2-pawn. Black would like to attack it with their knight as well. White must prevent the knight from coming to g4 or suffer the consequences. If White ignores the danger and plays a normal developing move like 6. Nc3?, Black can exploit this with 6...Ng4 7. Be3 Nxe3 8. fxe3 Bxe3, winning back their pawn. 6. Bg5??, thinking to pin the knight, instead springs a number of Stafford traps, the most infamous being: 6...Nxe4! 7. Bxd8? Bxf2+ 8. Ke2 Bg4#. Instead White must control the g4 square directly: 6. Be2 controls the square while developing a piece. Ultimately after 6. Be2, White would like to play c3 and d4, expanding central control until the Stafford gambit position suffocates. Black may try 6...Ng4 anyway, intending 7. Bxg4 Qh4, bringing an extra attacker to g4 while also threatening Qxf2#. White can just give back the piece and trade queens and be very happy 8. g3 Qxg4 9. Qxg4 Bxg4++. The more thematic continuation is 6...h5, supporting the knight going to g4 and with ideas of opening up the h file for Black's rook. Or, Black can try 6...Qd5, threatening Qxf2#. 7. O-O defends f2, and White can follow with c3 and d4. 6. h3 controls g4 with a pawn. These lines are broadly similar: one difference is that h3 allows 6...Bxf2+!? 7. Kxf2 Nxe4+, taking advantage of the fact the d pawn is pinned to White's queen. As they have not developed the bishop, White cannot castle if 6...Qd5 so must defend the f pawn with their queen. 6. f3 is the final way to control g4. This is similar to the 5. f3 line, and as in that line Black has the idea of 6...Nh4 intending ...Qh4+. The engine likes 7. Qd2 Qh4+ 8. Kd1 for White, though more natural is 7. g3 to prevent ...Qh4, where Black can 7...f5 intending ...f4 (the danger of which is illustrated in the line 8. Nc3 f4 9. Bxf4?? Nxf4 10. gxf4 Qh4+ ---). 6. Be3!?, to diffuse the threat by trading off bishops, is also a fair try for White and leads to a quieter game. The engine believes White gives up most of the advantage after 6...Bxe3 7. fxe3 and White must navigate threats on the e1-to-h4 diagonal. 6. c3?, though an important idea in the Stafford to prepare d4, is premature as Black can play 6...Nxe4 and the knight cannot be taken because of the tactic 7. dxe4?? Bxf2+! 8. Ke2 Bg4+ winning the queen. White can hold the position with 7. Qe2 Bxf2+ 8. Kd1 f5 + but it is far from comfortable. Theory table Stafford gambit with 5. d3 6. Be2 h5 7. c3! Ng4 8. d4 Bb6 9. h3 Nf6 +++ 6. ... ... 7. ... Bb6 8. a4 Be6 9. a5 Bc5 10. d4 Be7 11. Nd2 ++ 6. ... ... 7. O-O? Ng4 8. h3 Qd6 9. hxg4?? hxg4 10. e5 Qxe5 11. Bf4 -- 6. ... ... 7. Bxg4 Qh4 8. g3 Qxg4 9. Qxg4 Bxg4 ++ 6. ... ... 7. ... ... 8. Bxc8?? Qxf2# 0-1 6. Be3 Bxe3 7. fxe3 Ng4 8. Qf3 Qh4+ 9. g3 Qg5 10. Kd2 ++ 6. Nc3? Ng4 7. Be3 Nxe3 8. fxe3 Bxe3 - 6. h3 Bxf2+ 7. Kxf2 Nxe4+ 8. Kg1?? Qd4+ 9. Kh2 Qe5+ 10. Kg1 Qd4+ 11. Kh2 Qe5+ 12. Kg1 Qd4+ 13. Kh2 Qe5+ ½-½ 6. ... ... 7. ... ... 8. Kf3 Qf6+ 9. Kxe4 O-O unclear 6. Bg5?? Nxe4 7. Bxd8?? Bxf2+ 8. Ke2 Bg4# 0-1 6. ... ... 7. Be3 Bxe3 8. fxe3 Qh4+ 9. g3 Nxg3 10. hxg3 Qxh1 -- 6. ... ... 7. dxe4?? Bxf2+ 8. Ke2 Bg4+ 9. Kxf2 Qxd1 -- References Petrov Defence