Special Chess Moves: Castling, En Passant and Pawn Promotion Explained
The three special moves in chess, explained simply: when you can castle and when you can't, how en passant works, and how pawn promotion works, with free interactive lessons.
Most chess moves follow the simple rules of each piece. Three moves are different, and they confuse almost every new player: castling, en passant and promotion. Here is exactly how each one works.
Castling: the king's special move
Castling is the only move where two pieces move at once. The king moves two squares toward a rook, and that rook jumps over to the square on the king's other side.
- Kingside castling (short, written
O-O): the king goes to g1 (g8 for Black) and the rook from h1 to f1. - Queenside castling (long, written
O-O-O): the king goes to c1 (c8) and the rook from a1 to d1.
Castling does two jobs in one move: it tucks the king into safety and brings a rook toward the centre.
When you can't castle
You may castle only if all of these are true:
- Neither the king nor that rook has moved before in the game.
- All squares between the king and the rook are empty.
- Your king is not in check right now.
- The king does not pass through or land on a square attacked by an enemy piece.
En passant: the pawn's special capture
When a pawn moves two squares from its starting square and lands right beside an enemy pawn, that enemy pawn may capture it as if it had moved only one square. The capturing pawn moves diagonally to the square the other pawn skipped over.
Two rules make en passant unusual:
- It is only possible with pawns, and only against a pawn that just made a two-square move.
- You must do it immediately, on the very next move. If you wait, the chance is gone for good.
En passant exists so that a pawn cannot sneak past an enemy pawn by using its double step.
Promotion: a pawn becomes a new piece
When a pawn reaches the last rank (the 8th rank for White, the 1st for Black), it must be exchanged for a queen, rook, bishop or knight of the same colour, right away. You can have two or more queens on the board.
Almost always you choose a queen, the strongest piece. Choosing something else is called underpromotion, and it has two uses:
- A knight can give check or fork in a way a queen can't.
- A rook or bishop can avoid stalemate when a queen would leave the opponent with no legal moves.
A related rule: stalemate
If the player to move is not in check but has no legal move, the game ends in a draw by stalemate. It matters most when you are winning: always make sure your opponent has a move left, or make it checkmate.
FAQ
Can you castle out of check?
No. You can't castle while your king is in check. Deal with the check first; you may castle later if the king and rook still haven't moved.
Can you castle after moving the king back to its square?
No. Once the king has moved, castling is gone for the whole game, even if the king returns to its starting square.
Is en passant mandatory?
No. En passant is optional, like any capture, unless it is your only legal move. But you can only do it on the move right after the enemy pawn's double step.
Can a pawn promote to a king?
No. A pawn can become a queen, rook, bishop or knight, but never a king or stay a pawn.