[bug] Queenside castling allowed when pass-through square is attacked

I'm playing a game as black against "Cuzari83" as white. On move 24, he castled queenside while my queen on g6 is threatening b1.

king not moved through b1, so castle is allowed.

@vvilaplana would u mind sending the game link? i couldn't find it

here is: lichess.org/CaGQvZvA/black

Hi @vvilaplana,

The queen on g6 does not make the king castle through check. The rules of castling are:

- You can only castle if your king AND rook have not moved yet,
- You cannot castle during check,
- You cannot move your king through a check.

However, the rook can move through check and therefore it is a legal move.

Please message me further if you require more clarification.

Thank you very much,

CheerfulChessPlayer

Your queen was looking at b1, his king moved to c1, logically when he castled he did not enter check. This is allowed in chess.

I think @vvilaplana got confused with the rook castling during check, because the king did not castle through check.

If you want more practice, maybe this link could help:

lichess.org/learn#/14

Thank you very much and have a safe day everyone!

CheerfulChessPlayer

If it makes you feel any better, Korchnoi didn't know about that either!

Yes, this is correct. The rules about squares apply only to the King. (I teach my students that castling is a King move.)

You are free to castle Queenside with the Rook passing through b1/b8, and you can castle with a Rook that is attacked (rare, but legal.)

Once, a chess champion mistakenly castled queen with rook instead of king in an OTB match. I am unable to recollect who was he. @MrPushwood, do you remember this incident?