Lesson
White to move. Main line: 1. Nc3#
Nc3# vacates e2, opening the rook on e1 against the king on e8. The knight does not give check itself; its entire tactical purpose is to remove the final blocker from the rook’s file.
Black’s rooks occupy d8 and f8, while pawns on d7 and f7 fill the lower flight squares. The rook controls e7, and no defender can capture the distant rook or interpose on the already-open file.
Clearance mates reward attention to your own obstructing pieces. Trace rook, bishop and queen rays through friendly pieces, then ask whether a useful move by the blocker would uncover a forcing check.