Polish Defense

The Polish Defense is the reply 1...b5 to 1. d4. Its name comes by analogy with the Polish Opening, 1. b4, and it is closely related to the St. George Defense, into which it often transposes. The flank pawn covers c4, so White cannot easily set up the usual c4 and d4 pair, and it prepares ...Bb7 to place the bishop on the long diagonal. The price is that the b5-pawn becomes a target and Black does nothing directly to stop White from taking the center.

The standard objection is 2. e4, which is both the most common reply and the engine's first choice. White builds a pawn duo on d4 and e4 and also threatens 3. Bxb5, winning the pawn. Black usually answers with 2...Bb7, putting the bishop on e4 at once without defending b5. After 3. Bxb5, the Spassky Gambit Accepted, White keeps the extra pawn and Black relies on piece pressure against the center. Quieter replies such as 2. Nf3 and 2. Bf4 are also common. The engine also gives 2. Nd2 and 2. a4, the second of which attacks the advanced pawn at once. The engine rates the position as a slight edge for White. In practice White scores somewhat better, and draws are unusually rare, which suggests unbalanced games.

The opening was first played by the Polish player and analyst Alexander Wagner against Kuhn in the 1913 Swiss Correspondence Championship, and Wagner published analysis of it in Deutsches Wochenschach the following year. Reference works have mostly been skeptical. MCO-9 (1957) held that the opening failed for lack of central control. MCO-10 (1965) and MCO-12 (1982) softened this to say it had not been refuted, and I. A. Horowitz dismissed it entirely in 1964. MCO-14 treats lines where ...b5 is delayed by a move as considerably safer. One example is 1. d4 Nf6 2. Nf3 b5, sometimes called the Polish Defense Deferred.

The best-known high-level outing came in the 22nd game of the 1966 World Championship match. Boris Spassky, a point behind with few games left, chose 1...b5 against Tigran Petrosian. He reached equality but declined a chance to draw because he needed a win, and Petrosian won the game and kept his title. The opening remains an offbeat choice, valued mainly for surprise and for steering the game away from mainstream 1. d4 theory.