Bishop vs Disconnected Pawns: The Torn Bishop

A bishop can stop several pawns at once, but only if one diagonal covers all of them. When it has to be in two places, it is torn, and advancing a pawn at it is how you break it.

The mechanism. Push a pawn so the bishop must leave the diagonal where it is doing its other job. That is deflection, and it works whether the bishop is holding a passer or defending a pawn of its own.

The rescue. Here White is the one at risk, and he saves himself with 1.g6!. Giving the pawn up clears g5, the only square from which the bishop covers both c1 and f4, and it removes the f7 pawn that could otherwise have played f6 and chased the bishop away.

The flip side of a rule. The general rule is the opposite: keep your pawns off your own bishop's color, or the bishop goes bad. The exception is the defender in an opposite-colored bishops ending, where a pawn on your own bishop's color is out of the enemy bishop's reach, so only his king can come at it. The price is that the bishop is tied to it. That is exactly how a bishop becomes torn.

Three ways to tear a bishop. A bishop with two duties is torn, and chess slang has a blunter name for it: the pants, its two legs being the two diagonals. Push a pawn up one leg and the bishop must leave the other. There are three ways to break it: push a pawn at it, walk your king to the crossroads square and evict it, or fix everything and wait until zugzwang forces it to drop one job. The defense against all three is the same. Find the one diagonal that does both jobs, and get the bishop there in time.

In this drill three pawns come at you. Find the sacrifice and the one diagonal that does two jobs.