Answers.Body: <p>To look at this systematically, let's say white is attempting to triple-check black.</p>
  <p>At the start of white's move, black's king is not in check. So we have to go from zero checks to three checks.</p>
  <p>When a piece moves:</p>
  <ul>
  <li>the previous square it occupied becomes vacant (possibly creating a discovered check)</li>
  <li>the target square becomes occupied (possibly creating a check from this new position).</li>
  </ul>
  <p>These discoveries are possible:</p>
  <ul>
  <li>Pawn, knight or king moves: discovery by bishop, rook or queen.</li>
  <li>Bishop moves: discovery by rook or queen.</li>
  <li>Rook moves: discovery by bishop or queen.</li>
  </ul>
  <p>That only leads to two checks. (One unoccupied square can't cause two discovered checks because there is only one rank/column/diagonal between the king and that square).</p>
  <p>What other options exist? Do any of the special-case moves support a third check?</p>
  <h3>En passant</h3>
  <p>This causes <em>two</em> squares to become vacant – the square that our pawn moved from, and the square that contained the enemy pawn. So two discoveries are theoretically possible. Could this work?</p>
  <p>For a triple check, the king would have to be in the same file as the attacking pawn's starting position (to allow for discovery by a rook or queen), and on the 7th rank (to allow for check by the pawn as it reaches the 6th rank).</p>
  <p>For example, if white plays gxf6, black's king must be on g7. We have a position like this:</p>
  <pre><code>8/6k1/8/5pP1/4B1Q1/8/8/5K2 w - - 0 1
  </code></pre>
  <p>When the pawn captures, it opens up a discovered check along the g file. You can see that the removal of the black pawn cannot create a discovered check, as it is positioned a knight's move from the king, neither on a file, rank or diagonal.</p>
  <p>Alternatively, if the king was at g6, then the en passant move would create two discovered checks: the queen and the bishop. But it would not also be checked by the pawn.</p>
  <p>So, en passant can achieve:</p>
  <ul>
  <li>two discovered checks; or</li>
  <li>one discovered check, plus one regular check by the pawn;</li>
  <li>but not two discovered checks plus a regular check by the pawn</li>
  </ul>
  <h3>Castling</h3>
  <p>Castling causes two pieces to move at once, which sounds promising. But one of those pieces is a king, which can never give check, so it doesn't help. And since the rook starts from A1 or H1, it can never give a discovered check in the process, either.</p>
  <p>So, at best, castling yields one check.</p>
  <h3>Promotion</h3>
  <p>Pawn promotion sounds superficially interesting, but it's essentially like a normal move, that happens to start like a pawn and end like a queen or similar: a square is vacated, a square is occupied. Two checks are possible.</p>
  <h3>Double pawn move</h3>
  <p>The ability of a pawn to move two squares doesn't help: it's still vacating one square and occupying one other.</p>
  <h3>Conclusion</h3>
  <p>No, there is no way that three checks can be delivered with a single move in normal chess.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-10T02:16:34.433Z
Answers.LastActivityDate: 2021-11-14T23:12:47.587Z
Answers.LastEditDate: 2021-11-14T23:12:47.587Z
Answers.UserDisplayName: Steve Bennett
Answers.Body: <p>Triple check is possible in the chess variant known as <a href="https://en.wikipedia.org/wiki/Cylinder_chess" rel="noreferrer">Cylinder Chess</a>. In this position, 1.Ra8 discovers check from the queen and bishop, so it's triple or maybe quadruple check, depending on whether you count one or two checks from the rook, which is attacking the black king from two directions.</p>
  
  <pre><code>[FEN "4k3/8/8/8/R3K3/8/8/3Q1B2 w - - 0 1"]
  
  1. Ra8+
  </code></pre>
  
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Answers.CreationDate: 2017-08-08T10:53:23.033Z
Answers.LastActivityDate: 2017-08-08T10:53:23.033Z
Answers.UserDisplayName: bof
Answers.Body: <p>As others have pointed out, triple check is never <em>legal</em> in chess. It is, however, <em>possible</em>, even though no possible triple check is legal.</p>
  <p>One context where this is relevant is in framing the rules of the game. The rules must be written so as to enable the reader who does not yet know what is legal, to learn this. In <a href="https://chess.stackexchange.com/a/34862">this answer</a>, Brian Towers details a deficiency which at one time existed in FIDE's Laws of Chess which allowed triple check. (It's since been corrected.)</p>
  <p>Another such context is in writing a program which, given a chess position, generates all legal moves from it. A candidate must be rejected as illegal if it leaves the turn player's king in check from <em>at least one</em> enemy unit. It is possible that there are three, viz if the turn player is in double check and moves a pinned unit.</p>
  
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Answers.CreationDate: 2021-07-15T18:06:14.120Z
Answers.Text: Credit for the original research should, I think, go to R. Bosma who in 1993 noted the change in the FIDE Laws and realised the possible consequences. (See problem P1377135 at [PDB](https://pdb.dieschwalbe.de/search.jsp).) I acknowledge that you have written about this; so has Brian Towers, and so perhaps have others since 1993.
Answers.UserDisplayName: Rosie F
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Answers.UserDisplayName: Rosie F
Answers.Body: <p>The check itself defined as a player's king is under threat of capture by attacking piece(s) on next opponent's turn. According to standard chess rule, the pieces which can be counted as checking the king are pieces which <strong>able to move directly to the king's square.</strong></p>
  
  <p>These conditions counted as double check instead of triple check, assumed the pieces are attacking in one move:</p>
  
  <p>1) Rook <a href="https://en.wikipedia.org/wiki/Battery_(chess)" rel="nofollow noreferrer">battery</a> with queen/bishop/knight/pawn (second rook at the same file/rank not counted).</p>
  
  <p>2) Queen-bishop battery with rook/knight/pawn (whoever supporting piece at the same diagonal not counted).</p>
  
  <p>These conditions counted as single check instead of double:</p>
  
  <p>1) Queen-rook battery (or two rook battery).</p>
  
  <p>2) Queen-bishop battery.</p>
  
  <p>Also, <strong>triple check is impossible in standard chess</strong> due to <em>multiple checks must be executed in only one move</em>, which allows maximum of 2 pieces capable to attack the opponent's king directly at the same time (attacking pieces are neither subject to be captured nor interposed by other opponent's pieces).</p>
  
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Answers.UserDisplayName: Tetsuya Yamamoto
Answers.Body: <p>No.</p>
  
  <p>Even if you could like take a pawn en passant and open up two lanes in 1 move, only 1 lane will be mathematically relevant to checking the king.</p>
  
  <p>See, you can attack the king from a ton of directions, but all checking moves can mathematically only make 1 or 2 lanes/diagonal opened and thus relevant for delivering a check.</p>
  
  <p>Chess notation for diagrams use + for a single check and ++ for a double check, but I've never seen a +++ character for a triple check. They simply don't exist.</p>
  
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Answers.UserDisplayName: Sorin Solberg
Answers.Body: <p>Triple check is impossible, unless you want to count an x-ray attack as the third check.  A queen and rook attacking on the same file is normally thought to be one check.</p>
  
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Answers.CreationDate: 2017-07-19T01:37:00.723Z
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Answers.UserDisplayName: Fred Knight
Body: <p>In my logic, triple check not possible. Because I assume there is a move with two pieces at once needed. The only move I know is castling. The King can not give a check.
  So is triple check impossible?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2023-02-21T06:14:18.287Z
Comments.Text: Suppose an illegal move is played which goes unnoticed by the opposite player. If the kings lands on a place where there is already a check, followed by a discovered double check results in a triple check!
Comments.UserDisplayName: iammilind
Tags: <theory><check>
Title: Is triple check possible?
ThreadText: # Is triple check possible?
  
  (Asked by: username_0 on 2017-07-18)
  
  In my logic, triple check not possible. Because I assume there is a move with two pieces at once needed. The only move I know is castling. The King can not give a check.
  So is triple check impossible?
  
  **Tags:** theory, check
  
  > **Comments:**
  > **username_1**: Suppose an illegal move is played which goes unnoticed by the opposite player. If the kings lands on a place where there is already a check, followed by a discovered double check results in a triple check!  
  
  ---
  
  ## 6 answers
  
  ### Answer by username_7 on 2017-07-19. Score: 22 | Accepted answer
  
  Triple check is impossible, unless you want to count an x-ray attack as the third check. A queen and rook attacking on the same file is normally thought to be one check.
  
  
  ---
  
  ### Answer by username_2 on 2021-06-10. Score: 21
  
  To look at this systematically, let's say white is attempting to triple-check black.
  
  At the start of white's move, black's king is not in check. So we have to go from zero checks to three checks.
  
  When a piece moves:
  
  * the previous square it occupied becomes vacant (possibly creating a discovered check)
  * the target square becomes occupied (possibly creating a check from this new position).
  
  These discoveries are possible:
  
  * Pawn, username_7 or king moves: discovery by bishop, rook or queen.
  * Bishop moves: discovery by rook or queen.
  * Rook moves: discovery by bishop or queen.
  
  That only leads to two checks. (One unoccupied square can't cause two discovered checks because there is only one rank/column/diagonal between the king and that square).
  
  What other options exist? Do any of the special-case moves support a third check?
  
  ### En passant
  
  This causes *two* squares to become vacant – the square that our pawn moved from, and the square that contained the enemy pawn. So two discoveries are theoretically possible. Could this work?
  
  For a triple check, the king would have to be in the same file as the attacking pawn's starting position (to allow for discovery by a rook or queen), and on the 7th rank (to allow for check by the pawn as it reaches the 6th rank).
  
  For example, if white plays gxf6, black's king must be on g7. We have a position like this:
  
  ```
  8/6k1/8/5pP1/4B1Q1/8/8/5K2 w - - 0 1
  
  ```
  
  When the pawn captures, it opens up a discovered check along the g file. You can see that the removal of the black pawn cannot create a discovered check, as it is positioned a username_7's move from the king, neither on a file, rank or diagonal.
  
  Alternatively, if the king was at g6, then the en passant move would create two discovered checks: the queen and the bishop. But it would not also be checked by the pawn.
  
  So, en passant can achieve:
  
  * two discovered checks; or
  * one discovered check, plus one regular check by the pawn;
  * but not two discovered checks plus a regular check by the pawn
  
  ### Castling
  
  Castling causes two pieces to move at once, which sounds promising. But one of those pieces is a king, which can never give check, so it doesn't help. And since the rook starts from A1 or H1, it can never give a discovered check in the process, either.
  
  So, at best, castling yields one check.
  
  ### Promotion
  
  Pawn promotion sounds superficially interesting, but it's essentially like a normal move, that happens to start like a pawn and end like a queen or similar: a square is vacated, a square is occupied. Two checks are possible.
  
  ### Double pawn move
  
  The ability of a pawn to move two squares doesn't help: it's still vacating one square and occupying one other.
  
  ### Conclusion
  
  No, there is no way that three checks can be delivered with a single move in normal chess.
  
  
  ---
  
  ### Answer by username_3 on 2017-08-08. Score: 11
  
  Triple check is possible in the chess variant known as [Cylinder Chess](https://en.wikipedia.org/wiki/Cylinder_chess). In this position, 1.Ra8 discovers check from the queen and bishop, so it's triple or maybe quadruple check, depending on whether you count one or two checks from the rook, which is attacking the black king from two directions.
  
  ```
  [FEN "4k3/8/8/8/R3K3/8/8/3Q1B2 w - - 0 1"]
  
  1. Ra8+
  
  ```
  
  
  ---
  
  ### Answer by username_4 on 2021-07-15. Score: 3
  
  As others have pointed out, triple check is never *legal* in chess. It is, however, *possible*, even though no possible triple check is legal.
  
  One context where this is relevant is in framing the rules of the game. The rules must be written so as to enable the reader who does not yet know what is legal, to learn this. In [this answer](https://chess.stackexchange.com/a/34862), Brian Towers details a deficiency which at one time existed in FIDE's Laws of Chess which allowed triple check. (It's since been corrected.)
  
  Another such context is in writing a program which, given a chess position, generates all legal moves from it. A candidate must be rejected as illegal if it leaves the turn player's king in check from *at least one* enemy unit. It is possible that there are three, viz if the turn player is in double check and moves a pinned unit.
  
  > **Comments:**
  > **username_4**: Credit for the original research should, I think, go to R. Bosma who in 1993 noted the change in the FIDE Laws and realised the possible consequences. (See problem P1377135 at [PDB](https://pdb.dieschwalbe.de/search.jsp).) I acknowledge that you have written about this; so has Brian Towers, and so perhaps have others since 1993.  
  
  ---
  
  ### Answer by username_5 on 2017-08-08. Score: 3
  
  The check itself defined as a player's king is under threat of capture by attacking piece(s) on next opponent's turn. According to standard chess rule, the pieces which can be counted as checking the king are pieces which **able to move directly to the king's square.**
  
  These conditions counted as double check instead of triple check, assumed the pieces are attacking in one move:
  
  1) Rook [battery](https://en.wikipedia.org/wiki/Battery_(chess)) with queen/bishop/username_7/pawn (second rook at the same file/rank not counted).
  
  2) Queen-bishop battery with rook/username_7/pawn (whoever supporting piece at the same diagonal not counted).
  
  These conditions counted as single check instead of double:
  
  1) Queen-rook battery (or two rook battery).
  
  2) Queen-bishop battery.
  
  Also, **triple check is impossible in standard chess** due to *multiple checks must be executed in only one move*, which allows maximum of 2 pieces capable to attack the opponent's king directly at the same time (attacking pieces are neither subject to be captured nor interposed by other opponent's pieces).
  
  
  ---
  
  ### Answer by username_6 on 2017-07-26. Score: 3
  
  No.
  
  Even if you could like take a pawn en passant and open up two lanes in 1 move, only 1 lane will be mathematically relevant to checking the king.
  
  See, you can attack the king from a ton of directions, but all checking moves can mathematically only make 1 or 2 lanes/diagonal opened and thus relevant for delivering a check.
  
  Chess notation for diagrams use + for a single check and ++ for a double check, but I've never seen a +++ character for a triple check. They simply don't exist.
  
  
  ---
  
  