{"schema":"chessgrammar_motif_entry/1","slug":"discovered-attack","name":"Discovered Attack","aka":"discovery","category":{"key":"motif","label":"Direct tactics"},"edition":{"version":"v3.0","year":"2026"},"certified":true,"canonical":"https://chessgrammar.com/motifs/tactics/discovered-attack","tabs":{"identity":"https://chessgrammar.com/motifs/tactics/discovered-attack#identity","structure":"https://chessgrammar.com/motifs/tactics/discovered-attack#structure","examples":"https://chessgrammar.com/motifs/tactics/discovered-attack#examples"},"citation":"ChessGrammar (2026). Discovered Attack. In: ChessGrammar: A reference for chess concepts, Tactics grammar, edition v3.0. Entry cg:discovered_attack@1. https://chessgrammar.com/motifs/tactics/discovered-attack","variants":["by_king","check","double","double_discovered","on_queen","on_rook","pawn","plus_fork","plus_pin","with_capture","with_promotion"],"seeAlso":["fork","skewer","battery","double-check"],"definition":{"id":"cg:discovered_attack@1","statement":"A friendly piece moves off a ray and unmasks an attack against an enemy piece by a friendly slider standing behind it on that ray.","predicate":["Before the move, a friendly slider, a friendly piece of any type in front of it, and an enemy piece stand on the same line. The friendly piece is the only piece between the slider and the enemy piece.","The move takes that piece off the line. The move can be of any kind: a capture, a promotion, castling and an en passant capture all count. After the move, the slider attacks the enemy piece with nothing in between, and that enemy piece is not the piece captured by the move itself.","The gain must be real. The shape on the board is not enough. If the revealed attack targets the king, it counts automatically, because a king is never captured for material. Otherwise, the revealed slider alone must win that piece even against the opponent's best defence. A revealed attack the opponent can meet for free does not count. The whole move must net a real gain under best defence. A check by the moving piece, or a quiet clearance, that wins nothing is not a Discovered Attack. It is only an open line."],"diagnosis":"The nearest counter-case is a piece that leaves the line in front of a friendly piece that does not slide, such as a knight. Nothing is revealed at all, no matter how forcing the move looks. Only a sliding piece, a rook, bishop or queen, can attack along a line from behind. The counter-example shows exactly this case.","maturity":{"state":"stable"},"holotype":{"fen":"3r2k1/7p/3b4/p2N4/P4p2/1P5P/1P4P1/5RK1 b - - 0 34","move":"d6c5","san":"Bc5+","mover":"d6","unmasked":"d8","target":"d5","mover_target":null,"why":"The bishop moves from d6 to c5 and checks the king along the a7-g1 diagonal. Behind it, the rook on d8 now attacks the knight on d5. White has to answer the check first, so the knight cannot be saved, and Rxd5 wins it."},"nearMiss":{"fen":"3n2k1/7p/3b4/p2N4/P4p2/1P5P/1P4P1/5RK1 b - - 0 34","move":"d6c5","san":"Bc5+","mover":"d6","unmasked":null,"target":null,"mover_target":null,"why":"A knight stands on d8 instead of the rook. Bc5+ is still check and the bishop still leaves the d-file. A knight does not attack along a line, so nothing is revealed. White answers the check, and the knight on d5 is never attacked.","delta":"The rook on d8 is replaced by a knight, which cannot attack along the file it stands on. Everything else, including the trigger move, is identical.","neighbour":null},"nearMissPending":null,"standing":{"certified":true,"scope":"definition"}},"axes":[{"key":"revealed","name":"What the revealed slider attacks","values":["check","on_queen","on_rook"],"nature":"partition","note":"Target-type axis: all three values read the piece standing on the revealed target square, on the board after the move, and one square carries one type -- a true exclusion group. One value applies when the target is the enemy king (a discovered check); two more apply when the target is the enemy queen or rook. The complementary case -- the target is a bishop, knight or pawn -- carries no value of its own: it is the bare motif on this axis."},{"key":"cardinality","name":"How many friendly sliders the move newly reveals","values":["double_discovered"],"nature":"facts","note":"This value applies when the same move newly reveals two or more friendly sliding pieces attacking enemy material, not just the one the occurrence is built on. The complementary case (exactly one slider revealed) has no value of its own: it is the silent default on this axis."},{"key":"mover_effect","name":"What the blocking piece itself does or is","values":["with_capture","with_promotion","double","by_king","pawn"],"nature":"facts","exclusive":[["by_king","pawn"]],"note":"Facts about the blocker -- the piece that moves to reveal the attack: one value applies when the trigger move is a capture; another when the trigger move promotes; another when the blocker itself, after moving, directly attacks a second enemy piece besides the revealed target and the king; another when the blocker is the king. These four facts exclude nothing among themselves and can combine freely on the same case. A further value, for a pawn blocker, joins the king-blocker value as a blocker-type fact and, unlike the four facts above, is mutually exclusive with it: both read the piece type of the blocker before the move, and one square carries one type, so the two form their own exclusion pair, separate from the independent facts above. Structural implication, measured: the promotion value implies the pawn value, since only a pawn promotes -- both fire together."},{"key":"composition","name":"Co-tag with another certified object on the same move","values":["plus_fork","plus_pin"],"nature":"facts","note":"The composition axis records whether a Fork or Pin coexists with the discovered attack on the same move. The Fork value requires an effective fork; the Pin value requires a pin in the resulting position that touches one of the revealed attack's two poles. The values are independent of each other and of every other axis."}],"summary":"A piece moves aside to reveal an attack from a long-range piece behind it."}