Blackmar-Diemer Gambit Accepted

The Blackmar-Diemer Gambit Accepted is the position after 4...exf3. Here Black captures the second offered pawn instead of declining it with a fourth-move alternative such as 4...c6. White's choice of recapture largely determines the character of the game. The usual 5. Nxf3 develops a piece and leaves the queen guarding d4. White is then one pawn down, with a half-open f-file and a lead in development as compensation. The alternative 5. Qxf3, the Ryder Gambit, gives up the d-pawn as well, since 5...Qxd4 becomes possible, and it was the main subject of Diemer's own analysis. The recapture 5. gxf3 is rarely played and scores very poorly for White.

After 5. Nxf3 Black chooses among a family of named defenses: 5...Bf5 (Gunderam), 5...Bg4 (Teichmann), 5...e6 (Euwe), 5...g6 (Bogoljubow) and 5...c6 (Ziegler). The Ziegler is generally considered the most testing of these. Less common tries include 5...Nc6 (Pietrowsky), 5...c5 (Kaulich), 5...b6 (Ritter), 5...Qd6 (Holwell) and 5...Nbd7 (Schlutter). The engine gives Black a slight edge, yet in online games White wins noticeably more often than Black.