Pawn ram

A pawn ram, or simply a ram in Hans Kmoch's terminology, occurs when two enemy pawns face each other on the same file. Each pawn occupies the square into which the other would need to advance, so neither can move forward while the relationship remains intact.

A ram is a structural relationship, not an attacking move. It may fix one part of the board, block kings from crossing, and determine which bishop has useful or restricted diagonals. Several rams can form a barrier that is difficult to penetrate.

The two pawns cannot capture each other because pawns capture diagonally rather than straight ahead. Changing the structure usually requires an attack from a neighboring file, a piece exchange, or a side pawn break. A ram is therefore connected with pawn fixation, but differs from pawn tension, where the pawns can capture each other diagonally.