Patrol chess: definition and rules
Patrol chess
Definition
Patrol chess is a widely used fairy chess condition in which captures and checks are permitted only when the attacking or capturing piece is guarded (patrolled) by a friendly unit. In other words, unguarded pieces cannot capture, and an unguarded attack on the enemy king does not count as check. This condition transforms tactics and typical mating nets, making it a favorite in Fairy composition and problems under the umbrella of a special Condition.
Core rules (how Patrol chess modifies orthodox chess)
- Checks require a guard: A king is in check only from an enemy piece that is itself protected by a friendly piece. Unguarded attackers do not give check.
- Captures require a guard: Any capture is legal only if the capturing piece is guarded at the moment of capture. This applies to all pieces, including the king and pawns (en passant also requires the capturing pawn to be guarded).
- Non-capturing moves: Ordinary, non-capturing moves are unchanged; a piece may move without being guarded.
- Pins and guards: A pinned piece still “guards” for Patrol purposes even if it cannot legally move (guarding is about control, not move legality).
- Checks on your own king: As in orthodox chess, you cannot complete a move that leaves your king in check; however, only guarded enemy attacks count as check in Patrol.
- Castling, promotion, and other rules: Standard rules apply, but any immediate capture or check they would create/enable must respect the guarding requirement.
How it is used in chess
Patrol chess is primarily a tool for problemists and composers rather than over-the-board play. It creates striking effects in helpmates, selfmates, and directmates by transforming what “threat” and “defense” mean. Composers exploit guard-based permissions to craft paradoxical mates, quiet moves that “add a guard,” and rich interplay with other fairy conditions like Madrasi and Circe.
Strategic ideas and problem themes
- Guard-adding maneuvers: Quiet moves that add a single guard can convert a non-check into a check, or make a previously illegal capture legal.
- Decoy/Deflection of the guard: Luring or deflecting a guard piece turns off checks or disables key captures.
- Interference: Interposing between a guarding piece and its ward cuts the patrol line, instantly nullifying checks and captures.
- Switchbacks and echo: The same line becomes legal/illegal depending on whether a guard is re-established, producing elegant echoes and switchbacks in solutions.
- Paradoxical king walks: The king can sometimes stroll near “attacking” enemy pieces that are unguarded, because those attacks do not count as check.
Mini-diagrams and examples
These annotated positions illustrate the core Patrol effects. Note: The viewer displays standard chess; the captions explain how Patrol rules reinterpret the position.
Example A: Unguarded attack is not check
Position: White Kg1; Black Kg8, Qg2. In orthodox chess, the queen “attacks” the white king. In Patrol chess, Black’s queen is unguarded—so this is not check.
Diagram:
Example B: Add a guard—now it is check
Position: White Kg1; Black Kg8, Qg2, Bc6. The bishop on c6 guards the queen on g2 (c6–d5–e4–f3–g2). Now the queen’s attack is check in Patrol chess.
Diagram:
Example C: Captures require a guard
Position: White Kg1, Rg3; Black Kg8, Qg4. White would like to play Rxg4, but the rook on g3 is unguarded, so the capture is illegal in Patrol.
Diagram (before adding a guard):
If White first plays Kg2, the king guards g3; now Rxg4 becomes legal because the capturing rook is patrolled by its king.
Diagram (after adding a guard):
Why composers love Patrol chess
- Clarity of theme: “Guard toggles” make for clean, visible logic in helpmates and selfmates.
- Surprising refutations: Solutions often fail because a key attacker is unguarded, forcing an elegant preparatory move that “switches on” the attack.
- Synergy with other conditions: Combining Patrol with Madrasi immobilizations or with Circe rebirth rules yields highly original task records and echo mates.
Historical and cultural notes
Patrol chess rose to prominence through early 20th-century fairy chess experimentation and was popularized by problemists in journals dedicated to composition. It remains a staple “condition” in the repertoire of Chesss and Problemists for creating model mates, echoes, and neat guard-based paradoxes. You’ll frequently see it in annotated problem anthologies and modern solving contests.
Tips for solving Patrol chess problems
- Audit every guard: After each candidate move, list which friendly units guard the attacker/captor; unguarded attacks don’t count and unguarded captures are illegal.
- Look for quiet “guarding” moves: Moves that add a single guard often unlock the intended mate or key capture.
- Check interference lines: A single interposition can turn off multiple threats by breaking patrol lines.
- Remember the king guards too: King steps that add or remove a guard are surprisingly thematic in Patrol chess.
- Beware false checks: If you see “check” in an orthodox sense, confirm that the checking unit is guarded—otherwise it’s not a check in Patrol.
Frequently asked questions
- Do unguarded sacrifices work? You may move an unguarded piece, but if that move is a capture, it’s illegal. Unguarded “sacrifices” that rely on a capture won’t be permitted.
- Does a pinned guard still count? Yes. A pinned piece still “patrols” squares it controls; guard is about control, not the ability to move next.
- Is stalemate different? Stalemate is judged normally, but many positions that look winning in orthodox chess become drawn because intended checks/captures fail without a guard.
- What about en passant? The capturing pawn must be guarded for en passant to be legal.
Related terms and further exploration
Explore more composition concepts and fairy conditions:
- Fairy and Fairy
- Condition, Problem, Composition, Endgame
- Madrasi, Circe, Anti-Circe
- Classic themes: Interference, Deflection, Decoy, Line and Line
Quick practice prompt
Try to convert an orthodox “back rank mate” idea into Patrol chess. Which move must you add to ensure the mating rook or queen is guarded? How can the defender break the guard?