The King Is A Fighting Piece - Or Is It?

I AM slowly going through Tartakower & du Mont's 1952 classic, 500 Master Games Of Chess.
The games are arranged by opening, and within each opening by chronological order, where practical, to bring out the historical development of variations within an opening.
The book has been much-praised, not least because of this instructive method of presntation.

Tartakower's 500 … I got mine secondhand for £12

The following game is between the first winner of the British Chess Championship, the now largely forgotten Cecil de Vere, and Wilhelm Steinitz, who was to become the first officially recognised world chess champion.
It was Steinitz who famously said: "The king is a fighting piece - use it!" At least, he is often quoted on the internet as having stated that, although I have been unable to find a source for the quote. Anyway, I wonder if he recalled this game when giving his advice (assuming the advice came later).
De Vere - Steinitz
Dundee 1867
Ruy Lopez, Open Berlin
Notes in italics are by Tartakower (algebraicised) - other notes are by me
1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6
At one time Dr Lasker used to be the great protagonist of this active (if not too active) defence.
4.0-0
White disdains to protect his KP either by 4.Qe2 or more modestly by 4.d3, relying on the superior development which its capture would give him.
4...Nxe4
Challenging thunder and lightning on the K file in preference to adopting a more staid line of defence by 4...d6 (5.d4 Bd7 etc = Steinitz Defence) or 4...Be7 or even 4...Bc5.
5.Re1
Even more vigorous is 5.d4, strengthening the pressure on the centre files. The defence against 5.Qe2 presents no difficulties, eg 5...Nd6 6.Bxc6 dxc6 7.Nxe5 Be7 8.Re1 Be6 9.d4 Nf5 (not yet 9...0-0 10.Nxf7) 10.c3 0-0 with an equal game.
Carlsen and his most-recent world championship challenger Caruana are among strong players who have varied between picking 5.d4 and 5.Re1.
5...Nd6 6.Nxe5
Or 6.Bxc6 dxc6 7.Nxe5 Be7 followed by ...0-0.
6...Nxe5
Instead of this impulsive reply, which tries to eliminate the terrible threat Nxc6+, the coolheaded 6...Be7 is the coup juste.
Modern opinion tends to agree with Tartakower, eg John Cox in The Berlin Wall (2008) gives 6...Be7 without comment, as do Igor Lysyj & Roman Ovetchkin in The Berlin Defence (2012). However, Nakamura is one famous player who has played both moves.
Looking at my games, for what they are worth, I see I lost both times I played 6...Nxe5, and scored +2=3-4 with 6...Be7.
7.Rxe5+ Be7 8.d4?!
A choice that has not found favour over the following decades. Steinitz twice had this position 21 years later in his world title match against Zukertort. In game four of that match he played 8.Bf1 and lost; in game six he played 8.Nc3 and won. Today 8.Bf1 is most popular.

Steinitz had a penchant for exposing his king, but his next move takes that liking too far

8...f6?
An unsuccessful attempt to confiscate the opposing KB, which badly weakens the black king's battlements. As, on the other hand, 8...0-0 9.Bd3 would leave the white pieces with good attacking positions, simplification by 8...Nxb5 9.Rxb5 is the only resource.
The engines Stockfish10 and Komodo9 reckon Black is better after 8...Nxb5.
9.Re1 Nxb5
Again after 9...0-0 10.Bd3 White's pressure would be intensified.
10.Qh5+ g6
Stockfish10 strongly prefers 10...Kf8!? Komodo9 is unconvinced.
11.Qxb5 c6
After 11...0-0 Black's position would be no less awkward.
12.Qb3 d5 13.c4
This fight for the important diagonal a2-g8 marks an essential stage on the way to success.
13...Kf7
He resorts to artificial castling because after 13...0-0 14.cxd5 cxd5 15.Nc3 Black could not protect his d pawn and dark-square bishop.
14.Nc3
If now 14.cxd5 Qxd5 15.Qxd5 cxd5 16.Nc3 Bb4, and Black achieves equality.
14...dxc4?!
If 14...Be6 15.Qxb7.
The first piece of Tartakower's analysis that the engines strongly disagree with. They reckon that after a line such as 15...Qb6 16.Qxb6 axb6 17.cxd5 Bxd5 18.Nxd5 cxd5, Black's more active pieces give quite good compensation, although both Stockfish10 and Komodo9 prefer White.
Instead they declare 14...Be6?? a blunder thanks to 15.Rxe6! (15.cxd5, followed by later capturing on b7, also seems good) Kxe6 16.cxd5+ with a huge attack, eg 16...cxd5 17.Bh6! Rc8 18.Re1+ Kd7 19.Nxd5 Bd6 20.Qxb7+ Rc7 21.Nxc7, when White is material up and still attacking.
An uncredited annotator in ChessBase's 2019 Mega database gives 14...Qb6 15.Qxb6 axb6 16.cxd5 Bd6 17.dxc6 bxc6 "with compensation," although the engines again prefer White.
15.Qxc4+ Kg2 16.d5 cxd5?
This loses because it brings White's knight into a powerful central attacking position. The engines suggest 16...Re8 17.dxc6 bxc6 18.Be3 Bf5, but with a strong initiative for White after 19.Rad1 (Stockfish10) or 19.g4!? (Komodo9).
17.Nxd5 Bf8
But not 17...Re8 because 18.Nc7, nor 17...Bd6, after which Black's position remains precarious.
The engines reckon both moves cited by Tartakower are better than the game continuation, but that none can save Black.
18.Nxf6!
A far-sighted sacrifice which breaks up the black king's citadel.
Not the only way to win - White's advantages in development and king safety are too big - but one which makes Steinitz's "fighting piece" quote look out-of-place, at least in this game.
18...Qxf6
Or 18...Kxf6 19.Qc3+ followed by Qxh8.
18...Kxf6 19.Qh4+, winning the queen, is also rather good.
19.Bd2 b5 20.Qd5 b4
The terrible threat 21.Bc3 is past, but at the cost of multiple weaknesses.
21.Rac1
Instead of rushing for his prey by 21.Qxa8 Bc5 etc, White in a telling manner increases the pressure still more (threat: 22.Rc7+).
21...Qf7 22.Qxa8 Be6 23.Qe4 Bxa2 24.Qe5+ Kg8 25.Rc7
This irruption on the seventh marks the end of Black's resistance.
25...Qd5 26.Qxd5+Bxd5 27.Re8 1-0
(27...Bf7 28.Ra8 Kg7 29.Raxa7). A beautiful game.
Steinitz rarely lost so comprehensively, but he went on to much better things. And what of de Vere? He contracted tuberculosis, possibly around the time of playing Steinitz, became an alcoholic and died less than eight years later aged 28, according to Wikipedia.