Why can't the king castle in this position?

Question

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 03 '17 at 15:08
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 04 '17 at 19:11
I remember this game as one played by Steinitz in the Hastings 1895 tournament.. definitely not someone who should be annotated as NN. White later sacs a pawn by playing d5 so he can play Nd4 Nf5 so that he can put further pressure on the kingside. — N.S.JOHN, Jul 31 '21 at 07:09

score 42 · Accepted Answer · edited Oct 04 '17 at 00:20

42

Executive summary:

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

Detailed answer:

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.)

edited Oct 04 '17 at 00:20

Pablo S. Ocal

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answered Oct 03 '17 at 10:40

Yaron

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Ok, so it wouldn't be illegal, just a bad idea because white would lose a knight, correct? – garci560 Oct 03 '17 at 10:44
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@nprensen - correct - this is my understanding. – Yaron Oct 03 '17 at 10:44
@nprensen - did I answer your question? – Yaron Oct 03 '17 at 12:11
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@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 04 '17 at 13:11
@Paul yes you can, if you move it back to its original position. – Thorbjørn Ravn Andersen Oct 04 '17 at 20:34
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@ThorbjørnRavnAndersen From Wikipedia: "Neither the king nor the chosen rook has previously moved." – Paul Oct 04 '17 at 20:54
@Paul I'm pretty sure that I was taught what I say back in the 80'es but that was probably tightened later to ensure clarity. I cannot find anything to back this up, so I'm probably just plainly wrong :) – Thorbjørn Ravn Andersen Oct 04 '17 at 22:43

score 1 · Answer 2 · answered Oct 04 '17 at 09:35

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

answered Oct 04 '17 at 09:35

Justas

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Welcome to Chess Stack Exchange! While this is correct in general, this does not apply to the question at hand. – Glorfindel Oct 04 '17 at 11:45
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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. – Oct 04 '17 at 13:37
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You cannot move your king over a check to castle either. – johnny Oct 04 '17 at 17:35
@johnny But there is no check in this position. – Acccumulation Dec 14 '20 at 01:04

Why can't the king castle in this position?

2 Answers2