Alekhine's gun is a formation in chess named after the former World Chess Champion, Alexander Alekhine. This formation was named after a game he played against Aron Nimzowitsch in San Remo 1930, ending with Alekhine’s decisive victory.
The idea consists of placing the two rooks stacked one behind another and the queen at the rear. This can lead to massive damage to the opponent as it usually marks the beginning of the final assault (in this case it was only four moves before resignation). In rare cases it can be two queens and one rook on the same file.
Here is the game that spawned Alekhine’s gun:
Alexander Alekhine vs. Aron Nimzowitsch:
1. e4 e6 2. d4 d5 3. Nc3 Bb4 4. e5 c5 5. Bd2 Ne7 6. Nb5 Bxd2+ 7. Qxd2 0-0 8. c3 b6 9. f4 Ba6 10. Nf3 Qd7 11. a4 Nbc6 12. b4 cxb4 13. cxb4 Bb7 14. Nd6 f5 15. a5 Nc8 16. Nxb7 Qxb7 17. a6 Qf7 18. Bb5 N8e7 19. 0-0 h6 20. Rfc1 Rfc8 21. Rc2 Qe8? 22. Rac1 Rab8 23. Qe3 Rc7 24. Rc3 Qd7 25. R1c2 Kf8 26. Qc1 (See diagram. This is the point at which Alekhine forms the gun.) 26. … Rbc8 27. Ba4 (Threatening 28. b5, winning the pinned knight) 27. … b5 28. Bxb5 Ke8 29. Ba4 Kd8 (Guarding c7, so that the knight can move away on 30. b5) 30. h4! (But now all Black's pieces are committed to the defence against the gun, and he is running out of moves.) 30. … h5 31. Kh2 g6 32. g3 (Zugzwang) 1-0
Six years later, in 1936, William Winter was defeated in Nottingham by Alekhine, who used Alekhine's gun again to secure the victory. Since then, chess players have learned much about using and guarding against this formation. However, some international games are still lost and won by the force of this tactic.