Euwe Defense

The Euwe Defense, 5...e6, is the Blackmar-Diemer line analyzed by Max Euwe. Black shuts in the c8-bishop to build a French Defense type structure with an extra pawn. The kingside stays compact, and the plan is ...Be7, castling and a later ...c5 against d4. White relies on the half-open f-file, faster development and attacking chances against the black king.

The literature concentrates on 6. Bg5 Be7, after which 7. Bd3 is White's most popular choice. Black can strike at the center at once with 7...c5, while 7...Nc6 is regarded as the main line. Then 8. O-O Nxd4 9. Kh1 is the Zilbermints Gambit, which gives up a second pawn to sharpen the initiative. It scores well in practice but is probably not objectively sufficient. After 6. Bg5 Be7, White can instead play 7. Qd2, reinforcing d4 and preparing queenside castling with a kingside attack. In online play the immediate 6. Bd3, the Duthilleul Gambit, is by far the most frequent move and brings White strong results; 6. Bc4 is also seen. The engine slightly prefers Black, yet White wins considerably more often in practice.