The goal of chess is to trap the opponent's king through a checkmate. But a king cannot check a king in a chess match. It is illegal for a king to enter any of the squares that immediately surround the opposing king. Anyone who tries this move will be subject to a penalty. The person must then complete another action involving a different piece to try and keep the move going well.
An illegal move
One rule of chess entails ensuring the two kings on the board being safe from one another. A king controls all the squares that immediately surround it. He can hold eight spots if he's in the middle of the board, for example. The number of squares is less if he's on the edge of the board.
A player who moves one's king into one of the squares immediately surrounding the opposing king will be committing an illegal move. The king will enter a position where he must move one spot to get away from the check. But even then, that king could still check the other one.
Putting the King In danger
It is illegal for a player to move the king to a square where an enemy can capture him. The player is forcing a check instead of having the opponent try to figure out a check situation. The effort prevents the player from trying to think of some way to win.
While having a king check a king in chess sounds like it could work, it would be a foolish move by any player. The king can move one space in any direction he wants. Since the opposing king would be in an adjacent spot if the player gets away with this illegal move, the king could capture the other king and win the game.
An instance of perpetual checking
Any case where the king tries capturing a king could produce an instance of perpetual checking. The move occurs when a player tries forcing a draw through an ongoing series of checks. A king in danger could potentially move to one spot, but he would then be checked the next turn. He could move to another space, but he'll be checked once more. The process keeps on repeating to where the game ends in a draw.
But since it is illegal for a king to check a king, the offending player could be disqualified. That person has forced a perpetual check, possibly to keep a game one is not doing well in from becoming a loss.
The King requires movement
One rule of chess entails how the king needs to be free to move in any open space where he can go. The other pieces cannot obstruct a king's movement. The king cannot move into any squares that are controlled by the opponent's pieces. Any situation where the king's movements are restricted may be unfair to the player. It could result in a draw if the king has no further ability to win.
What happens if someone completes an illegal move?
If someone tries this illegal chess move, the most common thing to do is to alert that person and take the move back. The player would then have to go with another shift.
But other penalties may apply, especially in competitive tournaments. The arbiter for a tournament match might extend the amount of time a player has to make moves if that person's opponent tried checking a king with a king. Anyone who tries this move or any other illegal move twice in the match could automatically lose the game, although the judge may extend this to three offenses. The rules will vary by tournament and whatever the judge might determine.
Can the King still attack pieces?
While a king cannot check a king, the king can still attack other pieces. For example, there might be a rook and a knight in the spaces the king has control over. The king could attack and take the rook or knight if he wishes. This point assumes neither of those pieces is in a situation where they could check the king. But the player must be cautious, as it is still illegal to move the king to a spot where a check can occur after the shift. The player must also think about any possible moves the opponent could make to check the king after the move.
What about the Queen?
In addition to being illegal for a king to enter squares controlled by the opposing king, the king cannot enter spaces that the opposite queen holds. These include all squares in any of the eight directions that the queen can move. The king can still capture a queen if she is close enough to deliver a check.
A unique endgame with kings
There is one way how the two kings can interact with each other during a chess match. One endgame to watch entails the kings being separated by one square.
A player could move the king in front of a pawn while still having one square separating the two kings. The two players could move their kings around the board, while one player's pawn will continue to advance down the board. The piece can eventually be crowned as a queen if it reaches the end. At this juncture, the opponent's king will be open. It will become difficult for him to avoid the newly crowned queen. The queen can capture the king, and the game is over.
But the opponent can get one's king to move in front of the enemy pawn. By keeping that piece in between the two sides, the opposing king can stay in place. The player can shift one's other pieces back towards the king, creating extra protection. The pawn in the middle becomes neutralized, as it cannot move one diagonal spot to capture the king.
What if a stalemate occurs?
After a while, it might get to where the two kings are the only pieces of significance on the board. But in other cases, the king may be unable to move into any space. He may have limits due to a king, queen, or other pieces on the board controlling all the adjacent spots in the field. The king cannot move into check, so it is in a stalemate.
The stalemate occurs when the player has no legal moves, but the king is not in check. The game will end in a draw if there is a stalemate. But the player could also try to commit a swindle where the player tricks an opponent into moving a piece in one space.
But a swindle is extremely hard to complete, and it can take several steps to manage. It may also be easier to execute the work if there are more pieces on the board at a time.
Could time be a factor?
The last point surrounding whether a king can check a king relates to tournament play. Tournament competitors are subject to time limits over how much time they have to decide their next moves.
A player under significant time pressure might be rushed into moving one's king into the wrong spot. Sometimes the player might commit an illegal move and attempt to get the king closer to the opposing king. The arbiter will have the option of giving the opponent extra time or reducing the offending player's remaining time. This point makes it critical for a player to avoid doing the wrong thing when playing chess.
Other ways how someone can complete a check
While a chess player cannot complete a check with one's king, there are still many other ways how someone can execute a check. Here are a few examples:
- A player can produce a fork where the king is under attack from two pieces on two separate sides. The king will have fewer spaces for safe movements, as two pieces can work to capture the king.
- A sacrifice can work in some situations. A sacrifice involves the player giving up one piece to produce a better tactical position where the king might become more vulnerable.
- A check may work if the king has not castled. It can entail moving a piece over a space that the king would enter to complete the casting move. The effort reduces the king's flexibility, plus it keeps the rook from being in the middle of the board.
- A skewer can work by moving a piece to a spot where it can capture the king after moving of check. The king could move out, but the opponent can capture the piece protecting the king in the next turn. The move reduces the opponent's army, but it does give the opponent some time to find a new defense for one's king.
The player must figure out how to manage one's king while looking at the potential ways to capture the opponent's piece. The work is about producing enough space between the two parties to ensure there are no struggles over what works here.