The Castling Chess Move – Making the Castling Move in Chess

Castling in the chess game is a special move, which involves the king and either of the original rooks of the same color. The castling move consists of moving the king 2 squares towards a rook, then moving the rook onto the square over which the king crossed. It is considered a kings move.

Castling on the king side is sometimes referred to as castling short and castling on the queen side is sometimes referred to as castling long; the difference being whether the rook progresses two squares (a short distance) or three squares (a long distance).

The Castling move is only allowed if all of these conditions hold:

  • Neither the king nor rook must have ever moved previously to this move;
  • There must be no chess pieces between the king and the chosen rook;
  • The king mustn’t currently be in check and mustn’t end up in check either.
  • The king mustn’t pass through squares that are under attack by enemy pieces.
  • The king and the chosen rook must be on the same rank.

Castling is an important move to utilize in the early part of a chess game, because it serves a two-fold purpose. Firstly, it moves the king into a more protected position away from the board’s center, and secondly, it moves the rook to a more participatory position in the center of the chessboard.

When you have to decide on a side to try the castling move on, you should consider the trade-off between your king’s safety and your rook’s activity. Kingside castling is usually thought of to be slightly safer, because the king piece will end up closer to the edge of the chessboard. As a bonus, the king will protect all the pawns on the castled side.

When you decide on queenside castling, the king is moved closer to the board’s center and the a-file side pawn is undefended. The king is therefore then often moved to the b-file to help defend the a-pawn and to get the king away from the board’s center. Furthermore, queenside castling will require you to move the queen; and it could therefore take a bit longer to achieve than kingside castling. A positive aspect of queenside castling is that it places the rook more effectively on the central d-file. This means the rook is mostly instantly active, whereas this might take longer to achieve with kingside castling.

It is a more common occurrence for both players to do kingside castling and quite rare for both players to engage queenside castling. It is called opposite castling when one of the players rooks kingside and the other one queenside. When players are making castling moves on opposite sides, it usually causes a fierce battle as both chess players' pawns will be free to advance to attack the opposing king’s castled position without endangering the player's own castled king. An example of this is the Dragon chess Variation of the Sicilian Defense.