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Franz G Jacob vs Wilhelm Cohn
Munich (1900), Munich GER, rd 15, Aug-11
Spanish Game: Open. St. Petersburg Variation (C82)  ·  0-1
ANALYSIS [x]

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Kibitzer's Corner
Jul-30-06
Premium Chessgames Member
  An Englishman: Good Evening: Cohn was one of the great anvils of chess--he frequently took a heavy pounding--but he was a hammer in this game, possibly the first with the famous 16...Ng3 sacrifice in the Open Ruy. Jacob couldn't find the best line OTB (17.hxg3,fxg3; 18.Qd3,Bf5; 19.Qxf5!) and goes down to a guy who could say that for one game, at any rate, he was as good as Alekhine.
May-15-19
Premium Chessgames Member
  KEG: This game was played in the final round at Munich 1900. Jacob was mired in last place, while Cohn was fighting for a shot at sixth place (which he obtained thanks to this win and to Janowski's loss in the same round).

As <An Englishman> has noted, this game was the first time the 16...Ng3?! sacrifice was played in this variation of the Open Ruy Lopez. Great spot! Remarkably, the play here followed that in many later games, perhaps most notably Smyslov-Reshevsky in the 1945 USA-USSR Radio Match, and also Duras-Maroczy, Ostend 1906; Teichmann-Vidmar, San Sebastian 1911; Boleslavsky-Botwinnik, 1943; as well as later games by Tahl, Euwe, and Sokolov. Munich 1900 did not feature many lengthy opening lines from major tournaments, especially not in the games of tail-ender Jacob.

So An Englishman is quite right to laud Cohn for his discovery of 16...Ng3?! But Cohn's later feeble play here, missing numerous wins and then actually winding up in a losing position before Jacob blundered away the game, hardly warrants bracketing with Alekhine, who would doubtless have found one of the flashly winning combinations that eluded Cohn's grasp.

Incidentally, Jacob's 17. Re1 was probably better than 17. hxN as played by Smyslove, Boleslavsky and others. Jacob's (first) fatal error came on his 18th turn.

1. e4 e5
2. Nf3 Nc6
3. Bb5 a6
4. Ba4 Nf6
5. 0-0 Nxe4

Opting for the Open Ruy.

6. d4 b5
7. Bb3 d5
8. dxe5 Be6

The standard position in the Open Ruy.

9. c3

9. Nbd2 is also frequently played here, and 9. Be3 and 9. Qe2 are also known lines. The text is quite logical and gives White good chances.

9... Bc5

9...Be7 is the other main line here. The text is the more active line.

10. Nbd2 0-0
11. Bc2


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11... f5?!

Looking for a sharp struggle against the hapless Jacob. 11...Bf5 is sound and the most frequent choice. 11...Nxf2 (or 11...Bxf2+) is the Dilworth Attack which can be wild but often ends up yielding equality. The text suggests that Cohn may have prepared 16...Nd3?!

12. Nb3

As played here by Smyslov and by Burn, Teichmann, Boleslavsky, Averbakh, Keres, Stein, and Geller among others. 12. exf6 e.p. is also a reasonable choice.

12... Bb6
13. Nbd4 NxN
14. NxN BxN

14...Bd7 keeping both his Bishops looks more accurate, but who am I to question Reshevsky, Vidmar, Botvinnikk, Tahl, and Timman! Besides, if the text is not played, the exciting 16...Ng3 would not have occurred.

15. cxB

15. QxB ! (MCO-13). The text, which defends the e5 pawn and opens the c-file, looks logical. MCO-13 states that 15. cxB "leads to a very difficult position for both sides." That is certainly true, but the position looks better for White (unless the 16...Ng3 sacrifice is deemed sound).


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15... f4?!

15...c5 looks stronger, though so far as I can see it has never been played.

16. f3 Ng3?!


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This was Cohn's novelty that has been followed by many great players in his wake. Is it sound? I will address this issue in my next post on this game.

May-15-19
Premium Chessgames Member
  KEG: Post II

17. Re1

It is often said that the best way to refute a gambit is to accept it. Consistent with this adage, and consistent with the analysis on this site by An Englishman, Smyslov (and others) have accepted the challenge and played 17. hxN. But after 17. hxN fxg3 18. Qd3 (best) Bf5, White has to give up his Queen with 19. QxB RxQ 20. BxR. 20...Qh4 would leave the following position:


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The chances obviously all lie with Black. For example, if 21. Bh3 Qxd4+ 22. Kh1 Qxe5.

Jacob's 17. Re1 is surely better than that. Better still was 17. Rf2. By not taking the Knight, Jacob kept the h-pawn closed, retains his two Bishops, and need only play carefully to get the better game.

17... Qh4

Still trying to attack, but it looks futile after 17. Re1:


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But now Jacob threw away all the benefits of his prior good play:

18. Bxf4?

"?"--(Tournament Book)

Very weak. Jacob had a number of better moves, each of which would retain his advantage: e.g., 18. Qd2; 18. Bd2; 18. Bd3.

After 18. Bxf4? Jacob was probably lost:

18... RxB
19. hxN Qxg3

Cohn's attack now had new life:


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Jacob was already in trouble, and only made matters (much) worse with his next move:

20. Bd3?

The only legitimate hope lay in 20. Re3.

20... Raf8

20...Rh4 immediately would also have been crushing.

21. Re3 Rh4


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22. Bf1?

This lemon should have hastened Jacob's defeat. 22. Qe1 was the best chance to prolong the game.

22... g5

22...Bg4 or 22...c5 were also killers.

23. Rc1?

This further blunder was the best chance for Jacob to get blown out and take his leave from a tournament in which nothing had gone well for him. Had he been searching for some means to hold off the inevitable, Jacob would presumably have played 23. Qe1.

23... g4

"!"--(Tournament Book)

24. Rcc3?

Worse than hopeless. 24. Rxc7 was the only chance to hang on if Jacob wanted to suffer a bit more. The game now absolutely seemed over:


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To this point, Cohn had indeed (as An Englishman aptly notes) played like Alekine. But from here, as I will discuss in my next posts on this game, he morphed into Daffy Duck and turned an absolutely winning position (rated -80.00 by Fritz and -12.39 by Stockfish) into a losing position by move 30. This game might have earned Cohn a brilliancy prize. Instead, only horrific play by Jacob beginning on move 31 allowed Cohn to emerge with a win.

May-15-19
Premium Chessgames Member
  KEG: Post III

In giving the position after 24. Rcc3?, I should have appended: "Black to play and win."

When posed as a problem, the solution is not all that hard to find: 24...Rh1+ ! 25. KxR Qh4+ 26. Kg1 g3 27. Bxb5 [27. Bd3 Qh2+ is mate in four] Qh2+ 28. Kf1 Qh1+ 29. Ke2 Qxg2+ 30. Kd3 Bf5+ and White is toast (31. Re4 BxR+ 32. fxB Rf3+ 33. QxR QxQ+ 34. Kc2 Qf2+ 35. Kb1 g2 36. Rc1 axB).

But Cohn missed the winning combination and played:

24... Qf4?

"?"--(Tournament Book).

25. Kf2

The only chance.


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The position was nowhere as overwhelming as it was one move earlier. But the win was still there. So a new problem can be posed: Black to move and win.

25... g3+?

25...Rh1 would have been crushing; e.g., 26. Rcd3 Qh6 27. Ke1 Qh4+ 28. Kd2 Qf2+. 25...Qh6 or 25...Rh2 would also have won for Black.

The text gave Jacob an escape hatch for his King.

26. Ke2 Rh2
27. Qd2


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Thanks to Cohn's poor play, Jacob's King has practically found a safe haven. Cohn could still have tried to apply pressure with 27...b4 and would still have had some advantage. But yet again he played as if in a fog with:

27... Bh3?

Now Jacob's King skips to a sanctuary Cohn should not have permitted, and any advantage Cohn had enjoyed was gone.

28. Kd1 c5

"!"--(Tournament Book)

28...h5 was another good choice for Black here.

29. Re2

29. Rxc5 Bxg2 30. BxB RxB 31. QxR Qxd4+ 32. Ke2 Qxb2+ 33. Kf1 Qb1+ 34. Ke2 Qxa2+ 35. Kf1 Qb1+ would also have led to equality and to a drw by perpetual check.

29... Rh1
30. Re1


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The game now seemed headed for a draw, and had Cohn played 30...QxQ= that would seem to be the inevitable result. But Cohn continued playing like a lunatic with:

30... Qxd4??


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White to play and win.

31. QxQ??

Not this. 31. Rd3! was the move (31...Qf2 32. Qg5+ Kh8 33. Rd2 (trapping the Black Queen) QxB 34. RxQ RxR+ 35. Ke2 Rf2+ 36. Ke1 Rxg2 37. RxR BxR 38. f4 and wins.

31... cxQ
32. Rd3 RxB

"!"--(Tournament Book)

33. RxR Bxg2
34. Rg1 Bxf3+
35. Ke1 g2


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Once again, after all the twists and bumps, Cohn had a win. This time he didn't blow it.

May-16-19
Premium Chessgames Member
  KEG: Post IV

36. Rxd4

36. e6 was a better chance

36... Rf5
37. e6

One move too late. Jacob should have played 37. Kf2

37... Be4?

Not blowing the win, but giving Jacob a glimmer of hope. He should have played 37...Kf8 or 37...h5. He should not have given Jacob a chance to remove the powerful Black Bishop.


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Jacob now had a chance to make things tougher for Cohn with 38. RxB! dxR 39. Rxg2+ Kf8 and now Cohn would have to win a tricky Rook ending. But Jacob played:

38. Rd2?

Now the game was over.

38... Kf8
39. Re2?

To have any chance, Jacob had to play 39. R(either)xg2 BxR 40. RxB. After the text (39. Re2?), the game should have ended immediately:


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Black to move and win.

Not much of a problem is it? Cohn should have won immediately here with 39...Rf1+! 40. RxR+ (40. Kd2 RxR was obviously hopeless) gxR(Q)+ 41. KxR Bd3 allowing Black to reach an easily won King and Pawn ending.

But Cohn missed this and played:

39... Ke7?

This didn't blow the win, but it allowed Jacob to play on for a while.

40. Re3?

He again had to take the g2 pawn (with either Rook) to offer any resistance.

40... h5!

Finally Cohn got back on track.

41. Ke2?

41. Rh3 was the only way to prolong the game.

41... h4!


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42. Rh3?

He should certainly now have tried 42. RxB, though by now it was probably futile.

42... Rf4
43. Rh2 Kxe6


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44. Rgxg2

Too late for this to do any good.

44... BxR
45. RxB Kf5


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0-1

May-16-19
Premium Chessgames Member
  An Englishman: Good Evening: Excellent combination of historical research and computer analysis, <KEG>! Do have some questions about your work.

1. 15...c5 does look like an interesting pawn sacrifice. What have the silicon monsters said? Have they found an answer to 16.f3,Ng5; 17.dxc5,Qc7; 18.Qd4?

2. After the standard (and heavily analyzed) Queen sacrifice, you write that after 20...Qh4, "...the chances obviously all lie with Black." Are you certain of this? Smyslov disagreed and even followed your variation in Smyslov vs Reshevsky, 1945 leading to victory. Did Tiviakov vs I Sokolov, 1994 really overthrow theory that much?

May-17-19
Premium Chessgames Member
  KEG: <An Englishman>You raise two important questions.

1) The "silicon monsters" extant in my home rate 15...c5 as Black's best here, but still give White the edge. Fritz 15 rates 15...c5 as 0.54 as compared with 0.77 for Cohn's 15...f4. Stockfish rates 15...c5 as 0.52 and 15...f4 as 0.54

After 16 f3 Ng5 17. dxc5 Black is indeed in trouble. Better for Black by far is 16...cxd4 17. Qxd4 (17. fxN dxe4 gives Black excellent counterplay for the piece with two passed pawns in the center) Rc8! 18. Bb3 Nc5

Thus, 15...c5 is not necessarily a pawn sacrifice at all, just a way to obtain counterplay. The question is whether the 16...Ng3?! sacrifice is OK. If not, then Black does better to play 15...c5. If 16...Ng3 is playable, then I guess 15...f4 would be best after all. Since I don't think 16...Ng3 is good, I am in the 15...c5 camp.

2) With regard to the variation after White accepts the sacrifice that I give in the text, the position after 22...Qxe5 would be:


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Black has Queen and three pawns for Rook and two Bishops. Nominally, therefore, material would be about even. But White's pieces are stagnant. He has to do something with his c1 Bishop. Since 23. b3 is not available, the once chances are 23. Bd2 and 23. Rb1. In either case, Black is better; e.g., 23. Bd2 Rf8 24. b3 c5 or 23. Rb1 c5 24. Bd2 Rf8. In both lines, Black is bolstering his passed d-pawn and White has a tough defensive task ahead.

In the Smyslov-Reshevsky game in the 1945 Radio Match, Smyslov did indeed play the line in my earlier note, and tried 23. Bd2. In his commentary on the game, Smyslov seems to side with your view, since he stated that: "A very interesting position has arisen: in exchange for the Bishops and Rook Black has a Queen and will quickly get an avalanche of pawns on the Q-side. Who has the better chances in the sharp struggle about to commence? This question awaits a conclusive answer in further analysis. In [Boleslavsky-Botvinnik Sverdlovsk, 1943], Botvinnik continued here 23...c5 24. Rad1 Qxb2 25. Bf4 d4 26. Bxg3 d3 Evidently White's attacking possibilities are more real than the dangerous threat of the advance of Black's passes pawns." I respectfully disagree. Although Boleslavsky wriggled out with a draw, in the line quoted Botvinnik seems to have a won game.

In the Smyslov-Reshevsky contest, Reshevsky did not play 23...Rf8 (as I suggest) or 23...c5 (Botvinnik's move) but greedily grabbed a pawn with 23...Qxb2. Smyslov correctly played 24. Bf4, leaving the following position:


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The game looks up for grabs, but Reshevsky played 24...c5 (instead of 24...d4 as pointed out by Smyslov in his commentary), and Smyslov quickly got the better game with 25. Be6+ Kh8 26. Bxd5 Rd8 27. Rad1. From here, Reshevsky fell apart: 27...c4 (27...Qf6 was better) 28. Bxg3 c3? (28...Qf6 was better) 29. Be5! after which the game belonged to Smyslov.

But the above analysis suggests that Smyslov won not because he accepted the sacrifice but because of weak play by Reshevsky.

With best play, I still believe that after 20...Qh4 in the line I gave, the chances all lie with Black.

May-18-19
Premium Chessgames Member
  An Englishman: Good Evening: Very interesting work, <KEG>. In my playing days, the older players at my club called the position after 22...Qe5 "The Sea Dragon Variation" because they thought it might have been the first opening variation in chess history to get analyzed at least 20 moves. Always had doubts about the claim, but I get why they thought so.

You have found some intriguing ideas, and I hope they get a workout OTB someday, esp. that piece sacrifice after 17.fxe4,dxe4.

May-18-19  sudoplatov: On checking the statistics on Chess365, it seems that 17.Re1 has done badly (though I didn't check on errors or player strength.) 17.Rf2 did best. (For example, 18.Re1 scores 100% in Duras-Maroczy but that's not with best play.

It would be interesting to see what the correspondence players have analyzed here.

May-18-19
Premium Chessgames Member
  KEG: <sudoplatov>I agree that 17. Rf2 is probably best, though I would like to see how it and 17. Re1 would fare in over the board play--and in correspondence play.

In either case, 16...Ng3 was a fine try by Cohn in this game.

May-18-19
Premium Chessgames Member
  KEG: <An Englishman>I hadn't come across the name "The Sea Dragon Variation." If this wasn't the first opening variation to be analyzed 20 or more moves deep, it was certainly among the first. The fact that Cohn's 16th move was tried by Reshevsky and Botvinnik many decades later is a clear indication that it was a good practical chance over the board even if--as I now tend to think--it is not sound as a theoretical matter.
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