King

The King is the center piece of the game. It cannot be captured.

It moves one square in any direction.

A king is in check when it is under attack by at least one enemy piece.

It is illegal to make a move that places one's king into check. Once under check a move must be made to remove the check. The possible ways to get out of check are:

• Move the king to a square where it is not in check.
• Capture the checking piece (possibly with the king).
• Block the path of the check with another piece.

A piece may be unable to move because it would place its own king in check (it is pinned against its own king).

Notice that the black king is free to move to any adjacent square by selecting it.

The white king is under check and has adjacent squares that it cannot move to as they are under attack by the rook. Select it to view the available moves. Note that the available moves for other pieces is also restricted to those that remove the check such as the only valid queen move.

Checkmate & Stalemate

If it is impossible to get out of check as there are no legal moves then the king is under checkmate and the opponent has won.

If there are no legal moves available and the king is not under check then the game ends in a stalemate. This is a draw. This usually occurs because any move would place the king under a check.

There are a few other ways that a draw can be reached through play:

1. Threefold repetition: If the same board position and state has been reached 3 times then it is a draw.
2. Fifty move rule: If there has been no capture or pawn move in the last fifty moves by each player, and if the last move was not a checkmate.
3. Dead position: A dead position is defined as a position where neither player can checkmate their opponent's king by any sequence of legal moves.

There are two kinds of dead positions:

• Insufficient Material: Positions with only the following pieces make checkmate impossible.
• King against king;
• King against king and bishop;
• King against king and knight;
• King and bishop against king and bishop, with both bishops on squares of the same color.
• Other positions in which checkmate is impossible by any sequence of legal moves. This can occur in blocked positions where it is impossible for either side to make a capture. If this is not immediately recognized as a dead position the fifty move rule will eventually apply.

In the following the king will move into the corner. If the queen moves to g1 then it would be stalemate. Perform a checkmate by moving the queen to a8.

Castling

The king has a special move called castling.

This consists of moving the king two squares towards a rook, then placing the rook on the other side of the king, adjacent to it.

Castling is only allowed when the all of the following is met:

• The king and rook involved in castling must not have previously moved;
• There must be no pieces between the king and the rook;
• The king may not currently be under attack, nor may the king pass through or end up in a square that is under attack by an enemy piece (though the rook is permitted to be under attack and to pass over an attacked square);
• The castling must be kingside or queenside.

An unmoved king and an unmoved rook of the same color on the same rank are said to have castling rights.

In this setup castling rights are given to the white king and h1 rook and the black king and the a1 rook only. Play a kingside castle by moving the white king to g1. Notice that black performs a queenside castle.