Blackmar-Diemer Gambit Declined: Gedult Defense is a chess opening with the ECO code D00, part of the Blackmar-Diemer Gambit Declined family. It goes 1. d4 d5 2. e4 dxe4 3. Nc3 Nf6 4. f3 a6. White opens with 1. d4 (the queen's pawn) and Black answers 1... d5. After 8 moves it is White to move. After the last move Black is a pawn ahead in material. The lesson on the board explains every move of the line and lets you play it yourself; it is free.
The moves
1. d4 – White plays the pawn to d4
1... d5 – Black plays the pawn to d5
2. e4 – White plays the pawn to e4
2... dxe4 – Black captures on e4 with the d-pawn
3. Nc3 – White plays the knight to c3
3... Nf6 – Black plays the knight to f6
4. f3 – White plays the pawn to f3
4... a6 – Black plays the pawn to a6
About the Blackmar-Diemer Gambit Declined
After 1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3, Black does not take on f3 and plays ...c5, ...e3 or ...Bf5 instead. Black avoids White's attack.
...c5 hits d4 right away and opens lines for Black.
...e3 gives the pawn back but blocks White's dark-squared bishop.
Black develops quickly and avoids opening the f-file for White.