Wrong bishop

The wrong bishop is a situation in chess endgame when a bishop on the other color of square of the chessboard would either win a game instead of draw or salvage a draw from an inferior position (Rosen 2003:61); in other words, a bishop is unable to guard squares of the other color. This most commonly occurs with a bishop and one of its rook pawns, but it also occurs with a rook versus a bishop, a rook and one rook pawn versus a bishop, and possibly with a rook and one bishop pawn versus a bishop.

White wins in this position. The defender has the wrong bishop if it is on the same color as the corner where his king is confined. Black's bishop is on the wrong color of square for it to form a fortress in the corner (i.e. with the black king on the h8-square and the bishop on the g8- or h7-square). White wins:

There are some situations involving a rook pawn and the wrong bishop.

In an endgame with a bishop and a rook pawn, the wrong bishop is one that does not control the promotion square of the pawn. This position is a draw with either side to move. Black simply keeps his king on the a8-, a7-, or b8-squares (or b7 if the pawn advances) to keep the pawn from promoting. A draw because of stalemate is also possible. If the bishop were on the other color it could force the black king out of the corner and the pawn could promote and win (Müller & Lamprecht 2001:96–100).

A rook and a rook pawn always win against the wrong bishop, as in this position. The defender has the wrong bishop if it is the one on the same color as the pawn's promotion square. The winning procedure is to give up the pawn at the right time to get to a winning rook versus bishop endgame. If the bishop was on the other color, the defender may be able to form a fortress in the corner, as mentioned above (Fine & Benko 2003:468–69).

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