The Jaenisch Gambit arises after 1.c4 b5 in the English Opening. ECO code: A10.

History

Named after Carl Jaenisch (1813–1872), the Finnish-Russian chess theorist. Black immediately challenges the c4-pawn with this gambit, offering the b5-pawn to disrupt White's opening plans.

Strategic Themes & Plans

After 2.cxb5, Black can continue with 2...a6, aiming to recover the pawn and open the a-file for queenside pressure, or play 2...e6 with compensation through superior development. The gambit is considered playable but slightly dubious—White should obtain a small advantage with accurate play. It has surprise value at club level.