Castling is a special chess move players will often encounter at the start of a game. When the opponent castles, the king and rook are used simultaneously during a single turn. The move is only possible under a set of specific conditions.
The castling move is only possible once, under the precondition that neither the king nor rook has moved. The rules of chess don’t allow a player to castle twice during a single game. After one castling move is completed, the king has moved and castling is not allowed again.
New players should familiarize themselves with the four base rules of castling, to determine if the unique move is possible:
- The king and rook may not have moved yet (for the whole game)
- The king may not be in check
- The squares the king moves through may not be under threat by the opponent
- All squares between the king and rook must be empty
Why You Can’t Castle Twice In Chess
Under no circumstances can players castle again in a single chess game. The first base rule of castling determines that the king may not have moved yet. To castle twice, a king has to move twice. Castling twice would break the first base rule of castling.
Even when a player decides to walk their king all the way back to its starting square, double castling remains an illegal move. This is true even when the second rook hasn’t moved yet.
However, this does not mean that castling twice never happens in a game of chess. If a player walks its king back to the starting square, it might go unnoticed by the opponent. Even the player itself might have missed it — it doesn’t need to happen on purpose.
Double Castling Does Happen (By Accident)
In tournaments and during a friendly game of physical chess, it can happen that an error is made (it’s usually by accident). Both players may not have paid attention to the fact that a king or rook was already moved before.
Especially if both players are beginners, mistakes can be made. They might not have familiarized themselves with the aforementioned preconditions of the castling move.
Proper castling moves are usually done at the start of a game, when the chess pieces are being placed forward. The king is the leader in battle and needs immediate protection. The agile rook is the perfect candidate for this role.
Cheating Is Not Possible In Online Chess
While double castling happens in offline games, online games are definitely different. This includes the use of a chess app or chess website. Common platforms such as Chess.com or Lichess use a chess engine under the hood, which will keep a backlog of moves by all pieces.
Chess engines don’t allow players to cheat, not even by accident. Castling twice would only be possible during a game of chess in one way: a castling move by white, and then a castling move by black. But both players cannot castle again by themselves.
Players wouldn’t even be able to make illegal moves on the board if they tried (such as this whacky vertical castling move). The engine simply denies the possibility. Playing online would help new players understand special moves a lot faster, because they filter out the errors right away!