Back rank

A rank is a horizontal row of eight squares. A side's back rank is the row nearest that player: rank 1 for White and rank 8 for Black. The term is therefore relative to the side being discussed, rather than a fixed rank number.

In the starting position, the back rank holds that side's king, queen, two rooks, two bishops, and two knights. Those pieces may leave later, but the squares remain the side's back rank.

Back Ranks Remain After Pieces Leave

8

7

6

5

4

3

2

a1

b

c

d

e

f

g

h

Rank 1 is White's back rank and rank 8 is Black's back rank, even after some pieces have left them.

Rank 1 for White, Rank 8 for Black

The white knight has left g1 and the black knight has left g8. Even so, a1-h1 remains White's back rank and a8-h8 remains Black's back rank. These regions are identified by the side and the board coordinates, not by which pieces still occupy them.

1. Rank 1 is White's back rank and rank 8 is Black's back rank, even after some pieces have left them.

The phrase also appears in “back-rank weakness”: when a king is trapped by its own pieces, an enemy rook or queen may attack along that row and sometimes deliver checkmate, meaning an attack on the king for which no rule-allowed reply exists.