Cross-pin

A pin exists when a piece cannot leave a line without exposing a more important target behind it. In a cross-pin , the same piece is subject to two or more pins at once, usually along crossing ranks, files, or diagonals.

A pin is absolute when moving the piece would expose its own king to check, making that move illegal. It is relative when moving is legal but would expose a queen, rook, or another valuable target. Because each side has only one king, at most one part of a cross-pin can be absolute; the others must be relative or depend on another serious consequence.

One rook, two targets behind it

8

7

6

5

4

3

2

a1

b

c

d

e

f

g

h

On the d-file, the rook on d4 keeps the king on d8 out of the rook on d1's attack.

Two lines cross on the same rook

The black rook on d4 blocks two lines: the file toward the king on d8 and the fourth rank toward the queen on h4. Both restrictions act on the same piece.

1. On the d-file, the rook on d4 keeps the king on d8 out of the rook on d1's attack.
2. On the fourth rank, the rook on d4 shields the queen on h4 from the rook on a4.
3. The rook on d4 is the shared screen for one absolute pin and one relative pin.

The tactical consequence

The restricted piece may appear defended or able to escape, yet leaving one line exposes the target on the other. It can therefore become a hanging piece, one the opponent can capture for material gain, or cease to perform a vital defensive duty. The motif often belongs to a longer sequence that adds attackers or removes defenders.

A defense must address both lines. An effective defensive move may capture or chase away a pinning piece, interpose another unit, move one of the targets behind the pinned piece, or create a more urgent threat. Solving only one pin may not release the piece.