k Welcome to Knackie's Tactics Training. The examples are based on material of a Hungarian Chess School. They have been revised using Fritz and a bit of Knackie's brain.
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k The 8th Lesson features the theme 'Opening / Closing Diagonals'.
12
k After having seen Rooks in Action in Lesson 7 'Opening / Closing Files', it's now time for the Bishops.
15
k Let's first look at a few 'Opening Diagonals' examples:
10
k Example 1: Gereben vs Troianescu, Budapest 1952
3
bsetup
1
bsetup fen r1b1rqk1/5p2/5Pp1/ppp1B1Q1/8/1P1P3R/P5PP/5RK1
1
bsetup wcastle none
1
bsetup bcastle none
1
tomove white
1
bsetup done
1
wname Gereben
1
bname Troianescu
1
k If there were no pawn on f6, things would be easy: Rh8 mate.
13
k So how did white get rid of his own pawn f6?
20
g5g6
f7g6
f6f7
k Opening the diagonal ...
8
f8f7
h3h8
k mate
8
k Example 2: Morales vs Lehman,  Lipcse 1960
3
bsetup
1
bsetup fen r4r1k/2p3qp/3p4/p1nPp1P1/1pP1Bp1P/1P3Pn1/P4KNR/1Q2R3
1
bsetup wcastle none
1
bsetup bcastle none
1
tomove black
1
bsetup done
1
wname Morales
1
bname Lehman
1
k In this example, it is hard to believe that black could make use of a diagonal, but it happened.
19
k You get 40 seconds ...
8
40
c7c6
k What is this?!
7
d5c6
k Now you should see which diagonal black can use.
15
g7a7
k The white king is fixed on the diagonal g1-a7, so he can't escape the following discovered attack:
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g2f4
c5e4
k White resigned in view of a huge loss of material.
12
k Example 3: Mihaljcsisin vs Benko, Sarajevo 1970
3
bsetup
1
bsetup fen r2r2k1/1bq2pb1/6pp/2P1p3/1nBpN2N/6PP/2Q2P2/3RR1K1
1
bsetup wcastle none
1
bsetup bcastle none
1
tomove white
1
bsetup done
1
wname Mihaljcsisin
1
bname Benko
1
k White has a nice Bc4 and a couple of threatening knights, but his Queen is under attack.
17
k How did white react? 50 seconds ...
10
50
e4f6
k Opening the b1-h7 diagonal for the Queen.
10
k On BxN there would follow:
8
g7f6
c2g6
k The pawn f7 is pinned.
8
f6g7
h4f5
k And Qxg7 mate follows.
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back 4
k playing Kh8 is no better:
8
g8h8
c2g6
f7g6
h4g6
k mate!
8
back 4
k So, black tried:
7
g8f8
h4g6
f7g6
f6h7
f8e7
c2g6
c7c5
g6e6
k mate
8
k Example 4: Soto Larrea vs Ortega, Havanna 1955
3
bsetup
1
bsetup fen 1q3k2/4b3/2n1p3/p1PpPp2/P1bP1Pp1/2N1Q1P1/8/2N2BK1
1
bsetup wcastle none
1
bsetup bcastle none
1
tomove black
1
bsetup done
1
wname SotoLarrea
1
bname Ortega
1
k This example is more difficult, because the final move is hard to forsee.
15
k Black surely wants to activate his poor Be7.
11
k 60 seconds ...
7
60
c6d4
k Weakening the c5 square.
7
e3d4
k It is clear that black now attacks the pawn c5 with his queen.
13
k Is there a difference between playing Qa7 and Qc7?
25
k Let's first look at Qc7:
8
b8c7
c5c6
k You'll understand this strong defense only if you have seen the whole variation.
16
c7c6
c1d3
c4d3
d4d3
e7c5
k Black hasn't achieved very much.
9
back 7
k Let's now look at Qa7, which was played in the game. Does this really make a difference?
16
b8a7
c1d3
c4d3
d4d3
e7c5
g1g2
k So, what is the difference between the black Queen standing on c6 or a7?
15
a7h7
k That's it! Qh3 mate cannot be prevented.
10
k Example 5: Botvinnik vs Judovics
3
bsetup
1
bsetup fen r1b2r2/1p1nq1bk/1np1p1pp/p7/3PN2N/1P2B3/2Q1BPPP/2RR2K1
1
bsetup wcastle none
1
bsetup bcastle none
1
tomove white
1
bsetup done
1
wname Botvinnik
1
bname Judovics
1
k Former World Champion Botvinnik in action.
11
k How did Botvinnik exploit his superior position? ( the first move is obvious, but what about the second one? )
21
k 40 seconds ... 
7
40
h4g6
k Opening the threatening b1-h7 diagonal.
10
h7g6
k Which move to play next? Some discovered check?
20
e2h5
k Much better! Kh7 now loses after:
6
g6h7
e4f6
k Double-Check
6
h7h8
c2h7
k mate
5
back 4
k So black played:
7
g6h5
e4g3
k The queen on the open diagonal now prevents the King from going back home.
15
h5g4
h2h3
g4h4
c2e4
k and mate
8
k Example 6: Radulescu vs Trojanescu, Romania 1950
11
bsetup
1
bsetup fen r1b1rbk1/ppqn1pnp/2p3p1/4p3/2P1N3/2N1B1PP/PP2PPB1/2QR1RK1
1
bsetup wcastle none
1
bsetup bcastle none
1
tomove white
1
bsetup done
1
wname Radulescu
1
bname Trojanescu
1
k Let's look at a last example of the 'Opening Diagonals' theme.
13
k Black's 'fianchettoed' knight on g7 looks somewhat strange. That square surely better suits a bishop.
19
k How did white exploit black's strange setup?
11
k 60 seconds ...
7
60
d1d7
k Taking away the defender of the f6 square.
10
c8d7
e4f6
k Logical ...
6
g8h8
k White now showed the crucial idea of his combination:
20
e3b6
k A desperado move, which opens the c1-h6 diagonal for the white Queen.
14
c7d6
k A desperate try. Black wants to take on f6 when white plays Qh6, but of course, white does not play Qh6.
19
c3e4
k Defending the Nf6, threatening Qh6 followed by Qh7 mate, and attacking the Queen!
16
k Too many threats, so black resigned.
10
k Example 7: Reshevski vs Persitz, Haifa 1958
11
bsetup
1
bsetup fen 2brnrk1/p1n2p1p/1pqp1PpQ/2p1p1P1/2P1P3/3PNR2/PP2N1BP/R5K1
1
bsetup wcastle none
1
bsetup bcastle none
1
tomove white
1
bsetup done
1
wname Reshevski
1
bname Persitz
1
k Let's now switch to the more rare 'Closing Diagonals' theme.
10
k Here's an easy example. White wants to play Rh3 followed by Qxh7 mate.
15
k But unfortunately, the Bishop c8 defends the square h3.
12
k White logically played:
8
e3f5
k Closing the diagonal c8-h3.
8
k Rh3 followed by Qxh7 cannot be prevented, so black resigned.
13
k Example 8: Bachman vs Mayinger, Augsburg 1898
11
bsetup
1
bsetup fen 7k/3b4/1p5P/2p3K1/3pp1P1/1P2p3/P1P1B3/8
1
bsetup wcastle none
1
bsetup bcastle none
1
tomove black
1
bsetup done
1
wname Bachman
1
bname Mayinger
1
k This example from the last century nicely illustrates the closing diagonals theme.
16
k How did black succeed in promoting one of his pawns?
12
k 40 seconds ...
7
40
d7b5
e2b5
d4d3
k closing the diagonal a6-f1.
10
c2d3
e3e2
k The pawn will promote.
10
k Example 9: Saemisch vs Ahues, Hamburg 1946
11
bsetup
1
bsetup fen 1r5k/2q2p1p/p2p3B/5PQ1/n1p5/2b4P/PrB3P1/2R1R1K1
1
bsetup wcastle none
1
bsetup bcastle none
1
tomove white
1
bsetup done
1
wname Saemisch
1
bname Ahues
1
k Black's king is almost mated in this position. White just needs to cut off the Bc3 from protecting g7.
19
k How would you proceed?
8
k 35 seconds ...
7
35
f5f6
k The Bishop is cut off! Easy mate ...
10
c7c5
k Oh No!!!!!!! Black exchanges Queens :-((
10
back 2
k So white did of course NOT play f5-f6, but:
11
e1e5
c3e5
f5f6
k Now the idea works, as after Qc5+, white's Queen is not attacked anymore.
15
k Mate on g7 follows.
7
k Example 10: Pala vs Beni, Austria 1971
10
bsetup
1
bsetup fen 1r3r1k/1p5p/2qp1P2/4p3/p3n1N1/P4Q2/1PP4P/5RRK
1
bsetup wcastle none
1
bsetup bcastle none
1
tomove white
1
bsetup done
1
wname Palda
1
bname Beni
1
k In the last example of the Lecture, white would like to launch an attack upon the black king.
18
k It seems black has serious counter chances on the c6-g2 diagonal.
14
k How did white prepare the attack? 60 seconds ...
12
60
k If white tries to launch an attack with Nh6 immediately, there follows:
15
g4h6
f8f6
f3g2
e4g3
h2g3
f6h6
k and white is mated :-O
8
back 6
k So, white played:
7
g1g2
k Closing the c6-h1-diagonal.
8
e4g5
k Black would like to exchange Queens. How would you react?
25
g4h6
k If black now answers NxQ, there follows:
10
g5f3
g2g8
f8g8
h6f7
k mate!
8
back 4
k So, black tried:
7
c6f3
f1f3
g5f3
g2g8
f8g8
h6f7
k Just the same.
8
k That's all folks, i hope you enjoyed the Lesson.
11
k These and many more examples can be downloaded in Chessbase or Pgn-Format at http://webplaza.pt.lu/public/ckaber
21