Evans Gambit, Fontaine Countergambit

The Fontaine Countergambit answers the Evans Gambit with 4...b5. Black copies White's pawn thrust, so the c4-bishop comes under attack in turn and the c5-bishop is left where it stands. The symmetry favors White, who moves first. 5. Bxb5 is the usual reply and 5. bxc5 is also common, while engines prefer 5. Bxf7+, which exposes the black king. The engine gives White a clear advantage, and White scores very heavily in the few recorded games. The line is seldom played.