Knight vs Bishop and Pawn: The Dark-Square Blockade

Watch the method: press play to see the winning idea run, or step through it move by move.

Bishop against knight arguments are settled square by square, and no square matters more than the one directly in front of a passed pawn. When that square is the opposite color of the escorting bishop, a lone knight can blockade forever, a piece down in support and completely safe.

The wrong-color blockade. A knight parked on the stop square can only be evicted by force, and the bishop is constitutionally incapable of applying any: it will never attack a dark square in its life. The logic is the wrong-bishop corner all over again, promoted from a corner to the middle of the board. Whatever maneuvers White finds, the attacking force against d6 is one king, exactly what the knight is built to handle.

The covering circuit. When the king does attack the post, the knight does not cling: it steps to one of the squares that still guard d6 from a distance (b7, c8, e8, f7, minus the one your own king occupies) and returns the moment the threat passes. A knight guards its own post from four remote addresses, and a lone king can attack at most two of them at once, so there is always a free one to hop to. This is the same check-and-return loop as the basic knight blockade, with the bishop unable to touch d6 itself, though it is no spectator: hop off the circuit and it bites, as after 1...Nc4+ 2.Bxc4.

The evaluation habit: before trading into bishop versus knight with a passed pawn on the board, look at the color of the square in front of the pawn. Opposite color, with the defending king nearby, the knight blockades and the pawn stays put; same color, the bishop attacks the post and the knight needs its king to hold it. Past the sixth rank, check for zugzwang before you trust the color alone.