1820 J. S. Bingham tr. D. L. Ponziani i. ii. 26 Two minor Pieces, for a Rook and two Pawns, may be considered an equal contract.
1863 19 The Knight and Bishop, in contradistinction to the Rook and Queen, are termed minor pieces.
1993 4 Sept. 29/1 A third option is to manoeuvre your pieces..so that they are hovering near your opponent's king. One example of this strategy is the minor piece checkmate.