Portsmouth Gambit

The Portsmouth Gambit is a version of the Wing Gambit that arises once Black has played 2...Nc6. White gives up the b-pawn to deflect the c5-pawn from the center. The compensation consists of a half-open b-file, sometimes an open c-file as well, a freer long dark diagonal for a bishop, and the chance to build a broad center while developing quickly. If Black ignores the pawn, White can follow with bxc5 or advance it to b5 to harass the knight.

Acceptance is the usual response. After 3...cxb4 White does not play the normal Wing Gambit plan but strikes at once with 4. d4, and in many lines the push d5 forces the c6-knight to retreat to a5 or b8. Taking with the knight, 3...Nxb4, is the second most common choice; White then gains a tempo with 4. c3, and after 4...Nc6 continues 5. d4 to occupy the center. Declining with 3...e6 is seen occasionally. The engine regards the gambit as roughly balanced with a faint lean toward Black, yet White scores reasonably well with it in online play.