I wonder why is white move 18 in this game legal?
My understanding of the rules is that you cannot castle while one of the spaces between king and tower is being covered by an enemy piece.
Actually, FIDE says so:
www.fide.com/fide/handbook.html?id=171&view=article rule 3.8.b.2 unless I am reading something wrongly.
Any idea what happened there?
You did read something wrong. Actually, FIDE states that "Castling is prevented temporarily if the square on which the king stands, or the square which it must cross, or the square which it is to occupy, is attacked by one or more of the opponent's pieces". This means that you can't castle if the king is in check, or if the next two squares (in the direction of the castling) are attacked by one or more of the opponent's pieces.
What you thought is correct only in kingside castling, because there are exactly two squares between the king and rook. In queenside castling though, only the two squares next to the king matter. So, the castling in move 18 is legal, because the black queen only attacks the square that is next to the rook.
To give you a simpler answer than above. The queen is not controlling a square that the KING moves through, The rook can move through the queens controlled square just fine. But your king can not. Because it would be in check while passing that square. In this example. The king is not in check during or after his passage to the c1 square. Which makes it legal.
If we pretend for a second that the queen would have been on the square b3. It would have been illegal to caste long, because the queen would be controlling the d1 square, which the king would have to move across to reach c1
Kings cannot move into check, i.e. onto a square attacked by an enemy piece. This also means that during castling, the king cannot move THROUGH the attacked square either. But in that game the king did not move into or through check. The rook moved through an attacked square, but the rook can be attacked all it wants. You can't check a rook.
Satisfied?
Thanks!! Very interesting.
Viktor Korchnoi famously had to ask the arbiter about this in his 1974 Candidates game against Karpov.
Lest we forget my little gem ;)
It's legal because it does not come in contact with the king
Your game is a very nice game,Sarg0n
It's legal but stupid move.Would never be done in real chess.
