Danish gambit is King’s Pawn Opening that starts with 1. e4 e5 2.d4 exd4 3.c3. White sacrifices a pawn (and not one but two! as we will see) to get a good lead in development and a really dangerous attack with the bishops. However, it is pretty easy to refute this opening with black, but you have to know the variations.
Now black can either play Danish gambit accepted with 3…dxc3 or he can decline it and play 3…d5. Both are good options for black, but if you know the line, you would see that black is better off accepting the pawn.
Danish gambit accepted 3…dxc3
Now white can take back with the knight playing Nxc3 and be happy with a slight lead in the development. The position is similar to the Morra gambit of the Sicillian defense, but with black’s pawn on e7 instead of c7. But the spirit of Danish gambit is to go all in. White plays 4.Bc4 giving up another pawn. Black usually takes on b2 with 4…cxb2 5.Bxb2 and now white black has various choices.
Black has a few good choices. 5…d5 is the main line called the Sletcher variation. 5..Bb4+ and 5…Nf6 can also be player. Both are good. 5…d6 is a passive choice but still leads to equal position.
Black Plays 5…Bb4+
After 5…Bb4+, white plays 6.Nc3 with the threat of going either Qb3 or Bxf7+ followed by Qb3+ and take the bishop on b4. Black defends with 6…Qe7. The line can continue 7.Nge2 Nf6 8.0-0 0-0 9.e5 Bxc3 Bxc3 and even though white is two pawns down, the game is objectively about equal due to huge lead in white’s development. If black is not careful he can easily come under strong attack.
Black Plays 5…Nf6
At first sight, it looks unnatural to develop the knight on f6 because white can easily kick it by e5. But the line goes 5…Nf6 6.e5 Bb4+! This in-between move is important to remember. White can play 7.Kf1 d5! 8.exf6 dxc4 9.Qxd8+ Kxd8 10.exg7 Rg8 with good game for black.
or 7.Bc3 Bxc3 8.Nxc3 d5! Again with good game for black. It is important to remember this move …d5 for black. It leads to series of exchanges after which black has an extra pawn and white can’t make much of his lead in development. The endgame is comfortable for black.
Black Plays 5…d6
This move is passive and should be avoided since black has much better options. The line goes 6.Nf3 Nc6 7.0-0 Be6 8.Bxe6 fxe6 9.Qb3 Qd7 10.Ng5 Nd8 11.f4 with initiative for white!
The Sletcher variation (5…d5)
This is the main refutation for the entire Danish gambit variation.
By playing d5, black puts a roadblock to the wild white bishops. If white takes 6.exd5, the c4 bishop loses its power and black can develop naturally with …Bd6 or …Nf6. Taking the pawn with queen is not recommended for white because he is two pawns down and doesn’t want to go into the endgame straight away.
Therefore 6.Bxd5 is the main line. Note that white is now threatening Bxf7+ and black can’t play Kxf7 because the queen on d8 is hanging. But black has a nice refutation which must be remembered : 6…Nf6
But wait, doesn’t white win after 7.Bxf7+? Before moving further, try to find a beautiful resource that black created by playing 6…Nf6.
So the line goes 7…Kxf7 8.Qxd 8 Bb4+! and black’s h8 rook attacks the queen on d8!. White is forced to play 9.Qd2 Bxd2 10.Nxd2 and black has avoided a dangerous attack and achieved an equal endgame.
So white can choose not to go 7.Bxf7 and simply play 7.Nc3 and maintain initiative. The main line goes 7…Nxd5 8.Nxd5. And here white is threatening to play Nf6+. Black defends with 8…Nd7 and has nothing to worry about. The lines are still sharp in this position, but it is easier to play if black has reached here.
Danish gambit declined 3…d5
Let’s say your opponent played the Danish gambit with 3.c3 and you have forgotten the lines. You can choose not to accept the sacrifice on c3 and simply play 3…d5! 4.exd5 Qxd5 5.cxd4 Nc6 6.Nf3 Bg4 7. Be2 and in this position black has nothing to worry about. The position is equal.
Black can play 7…Bxf3 8.Bxf3 Bb4+ 9.Nc3 Qc4 with a good game.
As the lines have shown, white gets too ambitious with the Danish gambit, but his attack may only work if black doesn’t know the variations. The Danish gambit accepted is completely playable and even If you don’t want to accept the gambit, 3…d5 is always available. In any case, black has a playable position either an endgame after mass exchanges or an extra pawn or two as compensation in case white chooses to attack.