Castling is a move that can often create confusion when you first start learning chess. You realize that you can only move one piece at a time on your turn to play. This, we could say, constitutes one of the basic rules of the chess moves. However, there is one move that is the exception, and that is the castling rule.

What Is Castling?

It is one of the special chess moves that allow you to move 2 pieces at the same time. These two pieces are the king and the rook, and both white and black pieces can castle. Castling is a move between the king and the rook only. You cannot castle with any other pieces.

There are two types of castling: long castling and short castling. Long castling is done on the queenside and short castling is done on the kingside. It is important to mention that regardless of the type of castling you do, it can only be done once in the game. And it can’t be undone either.

The chessboard has two sides: the queenside and kingside. In the diagram, the yellow area represents the queenside. Therefore the red zone represents the kingside.

How to Castle?

To castle, we must move the king two squares towards the king or queenside. We also move the rook next to the king “jumping it”.

In this example, we can see that White castles short. So, his king moves from the e1-square to the g1-square. And the rook on h1 moves next to the king by “jumping” it from h1 to f1.

In Black’s case, we can see that he has castled long. So, his king moves from e8 to c8 and the black rook from a8 to d8.

This example will help you understand the difference between long and short castling. In long castling, the rook has a longer path to reach its square.

Why Castling Is the Most Important of the Chess Moves?

In chess, the control of the center is one of the most important aspects of the game. The most intense part of the battle occurs there. The basic center squares in chess are e4, e5, and d4 and d5. However, other squares are quite important and they are the squares c4, c5 and f4, and f5. Therefore, we can conclude that the center is a dangerous area for our king.

Due to this, castling is a very important move since in a single move we can save our king far from the center. At the same time, we apply another fundamental principle of chess, which is to connect your rooks.

Chess Rules of Castling

1. You cannot castle if there is a piece between the king and the rook.

In this example, White is free to castle short because there are no pieces between the king and the rook. That means that the f1 and g1 squares are available for both pieces.

2. In order to castle you must not have moved the king or the rook before.

If you moved the king you can no longer castle, neither short nor long. In this example, the white king cannot castle anymore. It doesn’t matter if the king returns to e1, White lost his right of castling for the whole game. On the contrary, Black can castle after moving the knight to g8, of course!

However, if you haven’t moved your king but have moved the rook to a1 for example, you can still castle short. In this example, you can see that despite that White moved the rook from a1 to b1, he still can castle on the kingside. White must first develop his pieces and only then he can castle on the kingside.

3. You cannot castle if you are in check

Please remember that when we are in check we can only:

1. Capture the attacking piece
2. Interpose a piece to obstruct the threat
3. Move our king to another square that is not being threatened. However, this does not imply castle.

In the next example, you can see that Black’s last move was bishop takes c3 (Bxc3+ in chess notation). Here White cannot castle because he is in check, so the good move for him will be pawn takes c3 (bxc3). Later White may castle.

4. You cannot castle if there is a piece or several pieces that control the square or squares that our king must cross to reach his destination.

In this example, White’s king cannot castle short because the g1-square is already controlled by the c5-black bishop. It will be illegal if you try to castle short.

In the next example, you can see that White’s last move was 10. e4?? It turns out that this is a terrible blunder because now White cannot castle. The bishop on a6 it’s controlling the f1-square. That means that the white king cannot pass on this square.

How to Annotate These Chess Moves?

In official tournaments, short castling is noted as “0-0” and long castling is noted as “0-0-0” regardless of which side made the move.

Examples

In the first example, we can see a short game. White developed normally by developing his pieces and castled short. This is a good example of how to play the opening. However, Black did the complete opposite. They started by developing their queen and they moved several times. They ignored the opening concepts and lost quickly.

The following example is a bit more complicated. After Black played Bb4, White had to analyze how to respond to the check. Incredibly, White’s best move is Ke2! This move loses any possibility of castling, but avoids material losses.

Something important that every beginner should know about chess is that although there are general rules that guide us on how we should play… many times these rules are broken depending on the position.

A player achieves mastery as he learns to differentiate when to apply and when to break the rules.

Puzzles

Now it is time for you to put into practice the knowledge you have learned. Try to solve all the following exercises.

Answers

1. No. The White king is in check.
2. Yes. There is no problem with 0-0-0.
3. No. Black’s queen is controlling the f1 and g1-squares.
4. No. White’s g7-pawn controls the f8-square.
5. No. The Black king is in check.

Conclusion

Castling in chess is one of the most important chess moves. In a single move, the king is protected and the rook is activated. However, there are many positions in chess in which it is not so critical whether or not to castle. As you learn more strategies in chess, you will understand when it is more important to castle or not.

So, now if you want to have fun, watch the next video and test yourself by trying to solve the puzzle. 😄