In the last post I played a game of chess against the computer. When typing up the game I noticed a possible royal fork, in this post I explore that.

I am still using glchess rather than an advanced chess program so I have to manually make all the moves again and hope the computer does too.

• White: Zeth
• Black: GNU Chess
• Date: 2008.10.25

The first seventeen moves are the same as before.

1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. O-O Nxe4 5. d4 exd4 6. Re1 d5 7. a3 Qf6 8. Bg5 Qe6 9. Nxd4 Qd6 10. Nc3 Be7 11. Bxe7 Qxe7 12. Nxd5 Qh4 13. g3 Qg5 14. Nxc7+ Kf8 15. Nxa8 Bg4 16. f4 Qg6 17. Nf3 Kg8

So the black king has moved to Kg8.

18. Nc7 ...

The White knight moves straight into action.

18. ... a6

Black starts the attack on the white bishop.

19. Nd5 ...

No time to save our bishop, we have to keep riding.

19 ... axb5

The bishop is dead, but he has not died in vain.

20. Ne7+ ...

Here is the royal fork. Because my knight is threatening both the king and the queen, black has to save the king, leaving the queen to die.

Note this is actually a three-way fork, it is also threatening the black knight on c6. Note that the computer cannot do Nxe7, because that will lead to white Qxd8++, checkmate in one.

20 ... Kf8 21. Nxg6+ ...

There we go, our knight has killed the queen. However, our hero's job is done, he can die with honour.

21. ... fxg6

White is now so far ahead with a queen, two rooks and a knight versus a rook, two knights and a bishop.

22. Rxe4 Bxf3 23. Qxf3 ...

With the overwhelming force, White can exchange the knight for a knight and a queen.

23 ... Kf7 24. b3 Rd8 25. a4 Nd4 26. Qd3 Ne6 27. Qxb5 Rb8 28. Qb6 Nf8 29. Rd1 Re8

White can now push forward.

30. Qxb7+ Nd7 31. Qxd7+ Kf6 32. Qxe8 ...

Mopping up the knight and the rook, leaving black with only pawns.

32. ... Kf5 33. Qe5+ Kg4 34. Qxg7 Kf5 35. Rde1 g5 36. Qxg5# 1-0

Chase the king for the mate!