1. Falling for 1... Qxd5
Take a look at the position after 1. d4 d5 2. c4 Nf6 3. cxd5 Qxd5 (D)
|Position after 3... Qxd5|
In Part 1 it was made clear that this is a poor choice of capture, since it exposes the queen very early in the opening. After 4. Nf3, Black's best response without retreating the queen is 4... Qa5, pinning the knight and threatening 5... Bb4.
After the natural looking 5. Bd2 Qb6 (D) we arrive at the following position:
|Position after 5... Qb6|
Notice that the Black queen is aiming at the hanging b2 and d4 pawns. Many beginners as White may panic and play something like 6. Bc1? in an attempt to save both pawns, throwing any advantage they have out of the window.
What they don't realize is that Black cannot take on b2! Doing so falls for a trap:
The trap on b2 is one variation that you must know when playing against the Marshall Defense!
2. Taking on b7 too early
Rewind to the beginning, and look at the position after1. d4 d5 2. c4 Nf6 3. cxd5 Nxd5 4. Nf3 Bf5 5. Qb3 (D):
|Position after 5. Qb3|
White threatens to take on b7. However, after Black plays Nc6, White cannot take the pawn immediately or risk getting into trouble. We have examined this trap in Part 2, but let us look more in depth to ram the point home:
Only after White has consolidated his position with moves like e4 (opening the diagonal to allow Bb5) and Nc3, then can he safely take the pawn.
This danger isn't confined to the Marshall Defense. Always think twice before you grab wing pawns in the opening!
3. Failing to convert the advantage
Many of us-- especially lower level players-- simply aren't able to convert the advantage that we get out of the opening. But this is no longer a question of opening skills, but more of your technique and strategic thinking.
I will support this with an example, again featuring Frank James Marshall with his namesake defense. In the following game Richard Reti-- himself a famous chess player and author-- played 4. Nf3 against Marshall, and avoided the trap on b7. But when the time came for him to capture the pawn, he instead entered a complicated variation, subsequently getting the short end of the stick when Marshall sacrificed 3 pawns for a strong attack:
|Marshall vs Reti, 1925|
From this 3 part series, I hope you have gained a better insight on how to punish Black for playing the Marshall Defense. While this opening may contain a few tricks that will surprise a beginner, it will not survive a test against stronger and more experienced players.
Part 1: http://nushsblackknights.blogspot.com/2016/01/beating-marshall-defense-part-1.html
Part 2: http://nushsblackknights.blogspot.com/2016/01/beating-marshall-defense-part-2.html