# Why can't the king castle in this position?

In a video I'm watching (requires register), it has this setup.

``````[FEN "r3k2r/pp1qn1pp/2p2p2/8/3P4/5N2/PP2QPPP/2R1R1K1 b kq - 0 1"]
[startflipped ""]
``````

The instructor says:

The king cannot escape, he cannot castle kingside or queenside, because of the white's pressure on e7 [...]. Black wants to escape this pressure by castling by hand.

I don't understand why can't black castle. It won't castle from, through, or into check. Why is it?

• Black certainly can castle for both sides, but if he does... you know that `Qxe7 Qxe7` followed by `Rxe7` winning the knight as well. White gaining material advantage afterwards. – Tetsuya Yamamoto Oct 3 '17 at 15:08
• He just means you better not castle. – johnny Oct 4 '17 at 17:34
• In other words, the king should not escape or castle to either side, because it would mean giving a queen and knight (and if he castles queenside, a pawn, for after `Qxe7 Qxe7` `Rxe7` Black can't defend both`... Rxb7` and `... Rxg7`) for a queen. – Monty Harder Oct 4 '17 at 19:11

Executive summary:

Black actually can castle, but if he does castle he will lose the knight and the game (due to material loss).

Black and White have equal material.

• The black knight is protected by two pieces: the king and the queen.
• The black knight is attacked by two pieces: the queen and rook.

If the king castles, the knight will be protected only by the queen, and White will be able to win the knight which will lead to a big material advantage: a knight, which is worth about 3 points.

"Castle by hand" (meaning moving the king and the rook over several turns until they reach a castle position) will allow Black to keep protecting the knight. (E.g. By moving the king to F7 to protect the knight, followed by a rook to E8, etc.)

• Ok, so it wouldn't be illegal, just a bad idea because white would lose a knight, correct? – garci560 Oct 3 '17 at 10:44
• @nprensen - correct - this is my understanding. – Yaron Oct 3 '17 at 10:44
• @nprensen - did I answer your question? – Yaron Oct 3 '17 at 12:11
• @nprensen Except if the king has been moved earlier in the game, then you're not allowed to castle. Or if a rook has been moved earlier, then you cannot castle with that rook. But that's probably not the case in this game. – Paul Oct 4 '17 at 13:11
• @ThorbjørnRavnAndersen From Wikipedia: "Neither the king nor the chosen rook has previously moved." – Paul Oct 4 '17 at 20:54

There is one possibility when castling would be illegal - if king has moved earlier in the game - then the move would be illegal.

• Welcome to Chess Stack Exchange! While this is correct in general, this does not apply to the question at hand. – Glorfindel Oct 4 '17 at 11:45
• This is the famous game Wilhelm Steinitz vs Curt von Bardeleben, 1895. Black hasn't moved the king before the position shown in the game. – user1108 Oct 4 '17 at 13:37
• You cannot move your king over a check to castle either. – johnny Oct 4 '17 at 17:35
• @johnny But there is no check in this position. – Acccumulation Dec 14 '20 at 1:04