Rook on the edge, active piece guards the escapes
A rook (or queen) delivers mate along the back rank or edge file, with a supporting piece controlling the squares the king might run to. Named after Harry Nelson Pillsbury, the American master who used the pattern in his short-lived but brilliant career. Often arises in endgames where the supporting piece is a knight, bishop, or even an active king.
Rook delivers mate along the back rank.
2 more clean runs (at any point) to reach Recall.
Black to move. White's rook just took on f5, leaving the king on e1 exposed. Black's rook on b2 has a clear path to the first rank.
Rook delivers mate along the back rank.
2 more clean runs (at any point) to reach Recall.