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Chess Opening Theory/1. e4/1...c5/2. Nf3/2...Nc6/3. b4
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Portsmouth Gambit rd bd qd kd bd nd rd pd pd pd pd pd pd pd nd pd pl pl nl pl pl pl pl pl pl rl nl bl ql kl bl rl
Portsmouth Gambit
A variant of the Wing gambit. White sacrifices the b4-pawn for a semi-open b-file and sometimes an open c-file, along with control of the center and quick development. This also frees up the a1–h8 diagonal. If Black declines the gambit, White has the threat of bxc5, or even sometimes b5.
In contrast to the regular Wing gambit, after /3...cxb4/, White will play 4. d4. In many positions d5 is a threat, forcing the knight to either go to a5 or back to b8.
If Black captures with the knight, White will attack it with 4. c3. After 4...Nc6, White will attack the center with 5. d4.
Theory table
.
1. e4 c5 2. Nf3 Nc6 3. b4
4
5
6
7
...cxb4
d4d5
exd5Qxd5
c4bxc4
equal
...Nxb4
c3Nc6
d4cxd4
cxd4e6
-1
...e5
b5Nd4
Nxe5Qe7
Nc4Qxe4+
equal