User:AlexLane/draftBDG

The Blackmar-Diemer Gambit is a chess opening characterized by the moves
 * 1. d4 d5
 * 2. e4 dxe4
 * 3. Nc3,

intending f3 on the next move. This gambit is considered an aggressive opening, though its soundness continues to be the subject of much debate both on and off the chessboard. Its roots lie in an opening known as the Blackmar Gambit, named after Armand Edward Blackmar, a relatively little-known New Orleans player of the late 19th century who popularized its characteristic moves (1. d4 d5 2. e4 dxe4 3. f3) and was the first player to publish analysis on the opening in the chess literature.

The popularity of the Blackmar Gambit, however, was short-lived, as it is basically unsound, allowing Black to easily equalize the position after White's immediate offer of the f-pawn on the third move with 3. ... e5!. The Blackmar Gambit is today almost never seen in serious chess play, on either the professional or amateur level.

The evolved, modern form of gambit owes its origin to the German master Emil Joseph Diemer (1908-1990), who popularized the interpolating move 3. Nc3, delaying the thematic f-pawn offer until the next move. The position resulting after 3. ... Nf6 4.f3 reflects the main line of the gambit, although other Black responses on move three are possible. After many years of analysis, Diemer wrote a book on the opening in the late 1950s, titled Von Ersten Zug An Auf Matt!" (Toward Mate From The First Move!"), with most of the published analysis devoted to the Ryder Gambit, characterized by the moves 4...exf3 5. Qxf3.

It is easy for Black to decline the gambit on the second move with 2...e6 (leading to a French Defense) or 2...c6 (leading to a Caro-Kann Defense), although doing so does not eliminate White's ability to offer alternative gambits such as the Alapin-Diemer Gambit or the Diemer-Duhm Gambit.

As with most gambits, White aims to achieve rapid development and active posting of his pieces in order to rapidly build up a kingside attack. It is believed that with accurate play Black can defend his position and consolidate his extra pawn to good chances in the endgame, so this opening is almost never seen in top-level play. It is, however, somewhat common in amateur play and a trusted weapon of many club players.

Below is a sample game (in algebraic chess notation) that features the unusual feat of Grandmaster Efim Bogoljubov beating Diemer with his own favorite opening:

Bogoljubov - Diemer, Baden-Baden 1952:

1. d4 d5 2. e4 dxe4 3. Nc3 Nf6 4. f3 exf3 5. Nxf3 g6 6. Bg5 Bg7 7. Qd2 O-O 8. Bc4 Nc6 9. O-O-O a6 10. d5 Na5 11. Be2 b5 12. a3 Bg4 13. Ne5 Bxe2 14. Qxe2 Qd6 15. Rhe1 b4 16. axb4 Qxb4 17. Nd3 Qb6 18. Qxe7 Rab8 19. Na4 Qb5 20. Nc3 Qb6 21. Na4 Qd4 22. Ndc5 Nxd5 23. Rxd4 Nxe7 24. Rd7 Nf5 25. Nxa6 Rbe8 26. Rxe8 Rxe8 27. Nxc7 Re1+ 28. Rd1 Rxd1+ 29. Kxd1 Nc4 30. Nd5 Nxb2+ 31. Nxb2 Bxb2 32. Ke2 Be5 33. h3 h6 34. Ne7+ Kf8 35. Nxf5 hxg5 36. Ne3 Ke7 37. Kd3 f5 1-0