Modern Defence: the 4...Nd7 trap

6 November 2026

The Modern Defence starts with 1.e4 g6. Black lets White build a big pawn centre and plans to attack it later, with the bishop on g7 aiming down the long diagonal. It’s a flexible, perfectly sound opening — but its slow, quiet set-up leaves room for one very natural-looking mistake.

After 1.e4 g6 2.d4 Bg7 3.Nf3 d6 4.Bc4, the move 4...Nd7 looks harmless: the knight develops and supports a later ...e5. But with White’s bishop on c4 eyeing f7, the f7 pawn is guarded only by the king, and the knight on d7 takes away the king’s and queen’s last spare squares.

The trap: 5.Bxf7+! Kxf7 6.Ng5+

White gives up the bishop to drag the king out: 5.Bxf7+ Kxf7, and then 6.Ng5+. Now the king has three squares — e8, f8 and f6 — and every one of them loses. The usual hiding place, g8, is still taken by Black’s own knight.

6...Kf8 — the royal fork

7.Ne6+ forks the king and the queen. Wherever the king goes, 8.Nxd8 wins the queen, and White ends up a queen for a bishop.

6...Ke8 — the trapped queen

7.Ne6 isn’t even check, but it doesn’t need to be: the queen on d8 has no squares at all. It is walled in by its own king on e8, knight on d7, bishop on c8 and pawns on c7 and e7. Whatever Black plays, 8.Nxd8 takes the queen.

6...Kf6 — straight into mate

Stepping forward is the worst choice: 7.Qf3# is checkmate. The queen checks along the f-file, the knight on g5 covers e6 and f7 and is protected by the bishop on c1, the pawn on d4 covers e5, and Black’s own pawns and bishop block the rest.

How to avoid it

The problem isn’t the bishop on c4 — it’s 4...Nd7 before the kingside is developed. With 4...Nf6 instead, the same 5.Bxf7+ Kxf7 6.Ng5+ just lets the king step to g8, and White has given up a bishop for a pawn. As a rule: when a bishop is aiming at f7, make sure your king has somewhere to go before you shut in your own queen.

Want to recognise finishing blows like 7.Qf3#? Learn the checkmate patterns, then test yourself in practice.