The French defense is a great defensive tool, as it often seems impossible to demolish black's pawn structure. Also, black has the powerfull c5 push that tries to destroy white's centre. So white often seeks refuge in gambits, such as the Diemer Duhm ( 1.d4 e6 2.e4 d5 3.c4 ) or the Alapin Diemer ( 1.d4 e6 2.e4 d5 3.Be3 ).
But sometimes black also overplays his hand in the opening, such as the little miniature I played on the chess.com website under 3' time control.
Blackmardiemergambit - xxx
1.d4 e6 2.e4 d5 3.Nc3
Something normal for a change
Not that good...
4.exd5 cxd4 5.dxe6 (diagram)
Black must now capture with the bishop but chooses to walk on the wild side
5...dxc3 6.exf7+ Ke7 7.fxg8=N (diagram)
The underpromotion into the knight is the only winning move.
7...Ke8 8.Qh5+ g6 9.Qe5+ Kf7 10.Bc4
And black wisely resigned here.
That's what happens when "die hard" defender try to live dangerously !