Blackmar Gambit

The Blackmar Gambit is the early form of the Blackmar-Diemer Gambit. White meets 2...dxe4 with 3. f3, challenging the e4-pawn immediately instead of first preparing the push with 3. Nc3. The opening takes its name from Armand Blackmar of New Orleans, who popularized it in the late 19th century and published the first analysis of it. The move order soon fell out of favor. Because the queen's knight is not yet on c3, Black can strike back with 3...e5. After 4. dxe5 Qxd1+ 5. Kxd1 Nc6 6. fxe4 Nxe5, Black regains a central pawn, trades queens with White's king displaced, and stands clearly better. Taking with 4. fxe4 is worse, because 4...Qh4+ wins the e-pawn while White's king is exposed. In 1889 Ignatz von Popiel introduced 3. Nc3, which led to the modern gambit.

In practice, 3...exf3 is by far the most common reply, and 3...Nf6 comes second. After 3...Nf6, White can transpose to Diemer's main line by developing the knight to c3. The critical 3...e5 is seldom played but gives Black the best results. The engine assesses the position as clearly better for Black. Even so, White scores slightly better than Black in online games.