This long collection is the result of computer-searching a database of games from the East Devon Congress this year (1999). I had 222 games to analyse, courtesy of Ian George who had the thankless task of bashing them all in: 111 from the Major section (U155), and 111 from the Premier (U205). Of these, exactly half were identified by Fritz 5 as having tactical blunders (see Appendix for notes on how this was done). The 111 blunders comprised 65 from the Major and 44 from the Premier.
If you would like to repeat the exercise for yourself, you can download the games from the Premier (CBH or PGN) and Major (CBH or PGN) and compare your computer's efforts to the results of my analysis (CBH or PGN).
Having had the games marked by Fritz, I then went through the games to decide which were real blunders and which were Fritz getting its wires crossed (see appendix). The resulting list of blunders I then inspected and tried to identify (a) what tactical device was at work, and (b) if there were typical errors of thinking going on. Here's an example:
Major (Round 4) 1.e4 e6 2.d4 d5 3.Nd2 c5 4.exd5 Qxd5 5.Ngf3 cxd4 6.Bc4 Qd6 7.0-0 Nc6 8.Re1 Nf6 9.Nb3 a6 10.Nbxd4 Nxd4 11.Nxd4 Qc7 12.Qe2 Bd6 13.h3 "Out of Book," says Fritz. 13...0-0 14.Bd3 h6 15.c3 b5 16.Bd2 Bb7 17.a4 e5 18.Nf5 Qc6 19.Qf1 bxa4


















































































20.Nxd6
Misses a trick.
[-0.28 Fritz 5.00: 20.Rxe5 Rad8 [not 20...Bxe5, 21. Ne7+] 21.Re7 Kh8 22.Nxd6 Qxd6 23.Re3]
Fritz assesses White's position at the end of the analysis variation as +?.?. When you dump the database out for printing, it unhelpfully strips all these assessments off, but they can be seen in the CBH database.
Psychologically, this is a missed opportunity. It is also a threat missed by Black, so both players made a mistake. Tactically, it's a decoy/overload combination, and two moves deep. I'm sure that Black overlooked the possibility of Rxe5, and missed it because it was a second effect of moving the White Queen from e2 to f1, defending against the mate on g2. My guess is that Brian also overlooked the possibility, rather than saw it and thought it a bad idea. Of course, I actually don't know enough about any of these games to be able to tell things like this for sure. Either player may have seen all this and more, although this begs the question why they didn't react to what they saw.
Three features dogged my research: these difficulties in post hoc interpretation, compounded by lack of context, and possible transcription errors. On context: some of the games I witnessed and was able to tell that one or other player was in time trouble, when some of the decisions taken might make a bit more sense. Or a player may have grabbed a draw against a higher-graded opponent. Also, I assume that the scores are accurate. Ian did mighty battle with idiosyncratic handwriting and moves scribbled in time pressure, but there are a couple of games where I can only assume some other move was played than the one recorded. (I once found a score sheet which started: 1. e4 e5 2. Nc6 Nc6 3. Nf6 Nf6 - a player new to algebraic, I concluded.)
What I have done below is a preliminary description of the blunders - a natural history, if you like, trying to classify and count my way through the range of horrors on view. The richness of chess - even this sort of chess - really requires deeper consideration than I have been able to give it so far, so please forgive this as work in progress.
Some tactics can be readily ascribed to more than one type, e.g. as above, overloading a piece defending against a fork. In these cases, I filed them under the earlier theme in the sequence.
The tactical themes found were as follows:
Left hanging:
Forks, double attacks:
Pins:
Overloading (decoys, ties):
Undermining (ties):
Unmasking (discovered attacks, jumps):
Nets (no retreat):
Mating patterns:
Queening combinations:
I suspect that these relative frequencies do not reflect their occurrence in normal play, that is, I think you are more likely to miss a fork or pin than to miss a piece hanging.
Let's see some examples, simple and more complex.
14.Nf3-g1


















































































With two points: one to secure the h-Pawn...
14...Qe7 15.Qxh5
...the other of which Black missed. 1-0
1. c4 e5 2.g3 Nc6 3.Bg2 Bc5 4.a3 "Out of Book," says Fritz. 4...a5 5.Nc3 Nf6 6.d3 0-0


















































































7.Bg5 White sets himself up for a basic tactic (Knight fork 7...h6 Black didn't notice!
21.Bh3


















































































Black is in difficulty here but his next move makes things worse, adding a pin to the threatened discovery. In fact, White's Knight is currently pinned to the Bh3!
21...Nd7
[2.50 21...b4]
22.Nxg7
[1.66 22.Qf2]
22...Kxg7 23.Qf2 Qe8 24.Be6 Ndf8 25.Qf7+ Kh8
Suicide, as Black realises.
1-0
Skewer


















































































Impeccable so far, says Fritz. Both sides overlook a standard skewer tactic. 48.Rg5+
[-0.56 : 48.Kd2 Rf1 49.c7 Rf8 50.Ke3 Rf3+ 51.Ke4]
48...Kf3 49.c7
[-1.28 : 49.Kd2 Ra1 50.c7 Ra8 51.Rc5 Rc8]
49...Re1
[0.81 : 49...Rc1+ 50.Kd3 Rxc7 51.Rf5+ Kg4 52.Re5 Rf7 53.Ke4]
See above, and also:
1. e4 e6 2.d4 d5 3.Nc3 Nf6 4.e5 Nfd7 5.f4 c5 6.Nf3 Nc6 7.Be3 cxd4 8.Nxd4 Nxd4 9.Bxd4 Be7 "Out of Book," says F5.. 10.Bd3 Nc5 11.Be2 Qa5 12.0-0 0-0 13.f5


















































































13...exf5
[2.31 : 13...Bg5 14.a3]
14.b4! Qxb4
Black goes down the main line
[3.47 : 14...Qd8 15.bxc5 Be6 16.Rb1 Qc7 17.Nb5]
15.Nxd5 Qa5 16.Nxe7+
1. e4 d5 2.exd5 Nf6 3.Nf3 Nxd5 4.Bc4 "Out of Book," says Fritz. 4...c6 5.0-0 Bg4 6.d4 e6


















































































White makes an unguarded move - or rather, an apparently guarded one.
7.Bg5
[-2.78 : 7.Nbd2]
7...Bxf3 8.Qxf3 Qxg5
Unmasking (discovered attacks, jumps):


















































































18.Nc3 Overlooking a series of masked attacks.
[-0.88 : 18.Qd3 ]
18...Nxd4 19.Na4
[19.Nxd4 Bxg2 20.Kxg2 Qxb2]


















































































32...Qb1 This is the real blunder: can Black guarantee to get the Queen out? 33.Kg2 Nf6 34.Bd3 Qc1 35.Rc2 Qd1 36.Ree2 Nh5 37.Rcd2 Qa1 38.Ra2 Qc1
[6.63 : 38...d5 39.Qxd5 Nf4+ 40.gxf4 Qxc3 41.Rec2]
39.Qxf7 1-0


















































































White has at last worked up an attack. 30.Nh5 Allows Black an opportunity to chase away the Queen.
[-2.16 : 30.Rc3 Qd8 31.Nd3 Bg5]
30...Bf8 allows mate in three!
[#3 : 30...Rg6 31.Qe3 Qxb2 32.Nf4 Rg7 33.a3]
31.Nf6 Not only missing the mate, but walks into a defensive tactic.
[-5.13 : 31.Nxg7 surely the most natural move on the board! 31...Qxd4+ 32.Rxd4 Bxg7 33.Qxh7#]
31...Rxg2+ 32.Kxg2 Bxh6 33.Rxh6 Kg7 34.Rxh7+ Kxf6 35.h4 Qxb2+ 36.Kf3 Rb4 0-1
King safety more generally was a very common theme, sometimes in more complex situations than that. Here's one I may get into trouble for:
30.Rh1


















































































Good move! Fritz scents mate coming up. 30...Rh6
[1.91 : 30...b5 31.axb5 axb5 32.Rh3 b4 33.Ng3 f4 34.Nf5+ Kf8 35.Rh8+]
31.Ng3
[1.22 : 31.Rxh6 Kxh6 32.g4 is the way to pursue it: 32...Rf8 (32...Rh8 gives in meekly 33.gxf5 Qe8 34.Rh1+ Kg7 35.f6+) 33.Ng3 Qb6 34.Kg2 Qxd4 35.e6 fxg4 36.Rh1+ Kg7 37.Rh7+ Kg8 38.Qg6+ Qg7 39.Qxg7#]
The beginners' favourite of back rank mates made a single appearance in the register of blunders:


















































































27...Re2
[4.59 : 27...Qd8 28.Qc4+ Kh8 29.Qe4 Qg8 30.Qxf4 Rxa2]
28.Qc4+
[-0.34 : 28.Rxe2 We're assuming the score is accurate, I suppose, but this looks a little better! 28...Qd8 29.Qc4+ Kh8 30.Re1 Qb8 31.Qxc6]


















































































And a final double blunder (time pressure notwithstanding):
60.Kxg5
[-4.56 : 60.Nd1 Ng6 61.Nf2 d2 62.Kf3 Nf4 63.Ke3]
60...Ne6+
[0.00 : 60...Nh3+ and White's poor Knight does the splits. 61.Nxh3 d2 62.Nf2 h3 63.Kf5 h2 64.Ke5 h1Q 65.Nxh1]
1/2-1/2
Intermezzo
1. d4 e6 2.Nf3 b6 3.g3 Bb7 4.Bg2 Nf6 5.c4 c5 6.d5 b5 "Out of Book," says F5.. 7.dxe6 fxe6 8.cxb5 Qa5+ 9.Nc3 d5 10.0-0


















































































10...d4 Not picked up by Fritz as an error. 11.Nxd4 Bxg2 12.Nb3
The intermezzo
12...Qc7 13.Kxg2
With another Pawn.
Attack and defence
Here, a failure to count:
1. e4 e6 2.d4 d5 3.exd5 exd5 4.Bf4 Nf6 5.Nf3 Bd6 "Out of Book," says F5.. 6.Bxd6 Qxd6 7.c3 0-0 8.Be2 Re8 9.0-0 Bg4 10.Nbd2 Nbd7 11.h3 Bh5 12.Re1 Re7 13.Bd3


















































































Black spurns an opportunity to get the advantage and instead gives up a Pawn. 13...Ne4
[0.88 : 13...Rxe1+ 14.Qxe1 Re8 15.Qf1 Qb6 16.Rb1 Qc6]
14.Nxe4 dxe4 15.Rxe4
Thinking errors
Missed threats
One-movers
Two-movers
Three-movers
Missed opportunities (i.e. missed threat, opportunity not taken)
One-movers:
Two-movers:
Three-movers:
Oversight/natural moves in normal positions
Failure of nerve/Bluffed
Failure of analysis
Bad moves in bad positions (the frying pan problem)
Slack moves in good positions (incisiveness)
Errors of judgement not analysis (Positional errors)
Time trouble
When our mind is on higher things, we can be laid low. Here's a few missed mates:
Candidates for blunder of the tournament must include any one-move oversights. We had more than piece left hanging and more than one mate in one.


















































































50.Nf1 Suicide.
[-#1 : 50.Kf1 a5 51.Rb8 h4 52.Rf8+ Ke7 53.Rg8]
50...Re2# 0-1


















































































25... Qd7
[#1 : 25...Rxe1+ 26.Rxe1 Qg4 27.h3 Qg5 28.Nf3 Qf6]
26.Qg6# 1-0 Oops.
In my youth such things were referred to as cheapos - a point gained through minimum effort. It's hard to describe these as two moves deep, more like two moves shallow!


















































































16.a3 Not best.
[-#3 : 16.e4 Nxd3+ 17.Bxd3 Bxa2 18.Rd1 Qe5 19.h4 Rd8 20.Qg5 Qxg5+]
16...Nxd3+ 17.exd3
[17.Kd1 Qe1#]
17...Qe1# 0-1
32.Rf3


















































































Black is under the cosh, but loses instantly:
32...Qe4
[#3 : 32...Nf4 33.Qf5+ Ng6 34.Nxf7 Bf4 35.Qh5+ Kg8 36.Rg1 Rab8 37.Nh6+]
33.Nf5+ (threat Ne7+) 1-0
What produces these errors?
One obvious theme is a move of the opponent with two points, one of which you miss.
Another is mood: a player ahead on material or with a strong attack may overlook opportunities for the defending side. Or a player who is being attacked may panic and find it difficult to focus on simple threats of the opponent, or become gloomy and stop looking.
Missed opportunities (i.e. missed threat, opportunity not taken)
White overlooks a tactic made possible by Black overlooking the threat - so every missed opportunity may also represent an error of the opponent, allowing you to carry out a threat that could have been prevented.
We can find examples of every depth, as above:


















































































A curious double oversight follows. 29...Bf3 That Bishop is en prise!
30.Kf2
White misses it!
Most people's idea of a one-mover is more like this:


















































































18...f6 ? 19.Rab1 ?
[-3.31 : 19.Qd5 forward! ]


















































































12.b4 Fritz reckons this a blunder
[-0.91 : 12.Qe2 ]
12...Nc6 with double attack on b4 and e5 13.a3 cxb4
17.Bc3


















































































Both sides get in a muddle here: Black need not shed a piece, and has a clever alternative. 17...Bxd4+
[2.88 : 17...Qxc3 neat, eh? 18.Nxc3 Bxd4+ 19.Qxd4 cxd4 20.Nd5]
18.Qxd4 of course
This is sort of a three-mover:


















































































Black now plays a series of moves which make a poor position fatal. 14...f6
[1.94 : 14...b4 15.Nb1 Qxc2 16.Bd3 Qc7 17.Nbd2]
15.exf6


















































































Natural, but risking letting an opportunity slip.
[0.06 : 15.Nxd5 exd5 16.Qxd5+ Kh8 17.exf6 Bxf6 18.Qxa8 Bxb2]
15...Bxf6 ? Overlooking White's idea
[1.03 : 15...Nxf6 16.Bd3 Bd6 17.Ne5 Nd7 18.Nxd5 Bxe5 19.Nxc7 Bxd4 20.Nxa8]
16.Nxd5 back on track 16...exd5 ? Unnecessary! White must have some idea in mind, and there's no need here to fall for it.
[2.81 : 16...Qxc2 17.Nxf6+ Nxf6 18.Bd3 Qc7 19.Qe5 Nd5 20.Qxc7 Nxc7]
17.Qxd5+ Kh8 18.Qxa8
That opportunity was only taken because it was re-presented.
After this, I suspect we are at the limit of what many players can analyse accurately without mistakes. Given a favourable wind, we might follow a given sequence some ten moves deep, but not reliably identifying or analysing all the alternative branches. Still, see if you can do better than the tournament winner here:


















































































27.g3 This weakening move sets Black up for a stock mate.
[-#5 : 27.R7a2 Bg5 28.h3 Qxh3+ 29.gxh3 Rxh3+ 30.Kg2 Nh4+ 31.Kg1 Nf3+]
27...Qh3 Sufficient but the game could have been decided simply:
[-7.66 : 27...Qxh2+ 28.Nxh2 Bxe3 29.Bf8+ Rcxf8 30.Kg2 Rxh2+ 31.Kf1 Rxf2#]
28.Ne2
[-#4 : 28.Qxd5 Bxd5 29.Rxc7 Bc4 30.Rxf7+ Kxf7 31.Nxe4 Bxf1]
28...Bxe3 29.Ng1 Qxh2+ 0-1
Oversight/natural moves in normal positions
We can see the fatal attraction of 'normal' moves in the games Dobber-Nielsen and particularly Belinfante-Wood. Here's another:


















































































13.Ba3
[-1.00 : 13.Rb1 Re8 14.Be3 Bc6 15.Rfd1 Qxd6 16.Rxd6]
13...Re8 Now White has chased the Rook to e8, he has pieces en prise on both e2 and a1!
1. c4 e5 2.Nc3 Nf6 3.g3 g6 4.Bg2 Bg7 5.b4 "Out of Book," says Fritz. 5...c6 6.Rb1 0-0 7.d3 d5 8.Bg5 Be6 9.cxd5 cxd5 10.Qd2 Re8 11.Nf3 Qd6 12.0-0 a6 13.Rfc1 Nbd7 14.Rc2 Nb6 15.h3 Rec8


















































































16.Nxe5 enterprising but flawed?
[-1.81 : 16.Rbc1 d4 17.Bxf6 dxc3 18.Qg5 Bxf6 19.Qxf6]
16...d4 Black is bluffed!
[0.25 : 16...Qxe5 A) 17.Bf4 must have been White's idea: 17...Qh5 18.Bf3 (18.g4 Nxg4 19.hxg4 Bxg4 20.e3 Bf3 21.Bxf3 Qxf3) 18...Qxh3 19.Bg2 Qh5 20.Bf3 Bg4;
Hard to see to the end, but there's no concrete line to follow up.
[ B) 17.Qe3 17...Nfd7 18.Qxe5 Nxe5 19.Rbc1 d4]
These are among the most interesting blunders, requiring a certain level of chess competence to achieve. Sometimes the failures are simple - like failing to count - and others are more involved.


















































































12.Nxe5 An attractive but flawed idea.
[-0.72 : 12.Bc4 b5 13.Be2 Nd7 14.Bh4 Nc5 15.Nxe5 Bb7 16.Bg3 Nxe4]
12...f6
Oops.


















































































White's next is a bright idea laid low by a miscalculation. 15.Nxd5
[-3.09 : 15.Nf3 Bxc3 16.bxc3 Nc7 17.bxa6 Bxa6 18.Bxa6 Rxa6 19.a4]
15...Nxd5 16.Bc4 Nef6 17.Qf3 e6 18.Re1 Re8
1. e4 c5 2.Nf3 d6 3.Bc4 Nf6 4.Nc3 e6 5.d4 cxd4 6.Nxd4 a6 7.a4 Be7 8.Bb3 "Out of Book," says Fritz. 8...0-0 9.0-0 Nc6 10.f4 Qc7 11.Kh1 Bd7 12.f5 Nxd4 13.Qxd4 e5 14.Qd3 Bc6 15.Bg5 Rad8 16.Rae1


















































































A thematic break, but is it sound? 16...d5 17.Qg3 Bluffed!
[-0.47 : 17.Bxd5 h6 18.Be3 Ng4 19.Bd2 Bc5;
17.exd5 Nxd5 18.Bxe7 Nxe7 19.Qe2 also wins a Pawn;
17.Nxd5 is the most obvious line to analyse, and it is not bad for Black: 17...Nxd5 18.exd5 Bxg5 19.Qg3 Bxd5 20.Qxg5]
I put this one under 'analysis' rather than the similar example above which was 'bluffed'; this one is a short line which I guess White failed to analyse, the one above was a long line which I'm sure Black looked at but feared ending badly.
Bad moves in bad positions (the frying pan problem)
The phrase 'bad moves in bad positions' is from Hugh Alexander. Partly this is statistical: when you stand worse, fewer of your moves will not lead to trouble. One can have sympathy. But it is also psychological: panic, depression or a general lowering of expectations can all cause decision-making and chosen moves to become poorer. I saw loads of these...
20.Rae1


















































































20...Be7 Making a bad situation worse.
[2.09 : 20...Bc7 21.Rf6 h4 22.d6 hxg3+ 23.Kxg3 Bd8 24.Rxe5+ Kf8 25.Rf4]
21.Rxe5


















































































21...f6 Not cutting his losses.
13...cxb4


















































































14.Qb3 makes the worst of a bad job
[-2.56 : 14.Bb2 ]
Slack moves in good positions (incisiveness)
This was almost as common as the 'bad to worse' pattern: not really being in top gear when looking at a favourable position. There are many factors at play here: nerves, complacency, laziness and more.


















































































When you see a good move, stop and think again... 22.Qxa8
[-2.00 : 22.Bh6 ...There might be a better one! This move gets the Bishop off the hook with tempo 22...Re7 23.Qxa8 Bxh2 24.Rbd1 Qe5]
14.Qb3 makes the worst of a bad job
[-2.56 : 14.Bb2 ]


















































































14...bxa3 Black does not exploit his advantage in the best way.
[-1.19 : 14...Nc5 15.Qa2 Nxd3 16.Rd1 Nxc1 17.Raxc1 bxa3 18.Nxd4 Nxe5]
(One game with three characteristic blunders!)
16.a4


















































































16...0-0-0 Into the fire.
[2.44 : 16...f5 17.axb5 fxe4 18.Nxe4 Qc7 19.bxc6]
17.axb5 Nxd4 18.Rxa7
[0.59 : 18.Nxc4 is rather better 18...Nxf3+ 19.Qxf3 Qc5+ 20.Kh1 Qxc4 21.Qxf4 Qc5 22.Qxf7]
Errors of judgement not analysis (Positional errors)
Fritz can occasionally identify a move as a blunder, as far as I can tell on positional grounds. Sometimes I agree with it!
Here's an example of what I mean:


















































































20.0-0 allows Black to seize the seventh
[-1.09 : 20.Rd2 Nc6 21.0-0 Ke7 22.Rfd1 Rhd8]
20...Rb2 21.Rfe1 Rxa2
More typical are positional errors Fritz ignores:
1. e4 d5 2.exd5 Qxd5 3.Nc3 Qa5 4.d4 c6 5.Nf3 Bf5 6.Be2 e6 7.0-0 Nf6 8.Re1 "Out of Book," says Fritz. 8...Nbd7 9.h3 Be7 10.Bf1 0-0 11.Nh4


















































































Black mistakenly allows White to secure the two Bishops and a Queen's-side majority. 11...Rfe8 12.Nxf5 exf5
Time control here was at move 40, so any game which degenerates around move 35 or even earlier could be due to clock pressure. Time trouble doesn't provide a complete explanation for out-and-out blunders, but it does produce them. We saw one I guess in Evans-Dunn.
Conclusions and recommendations
Well, what do you think?
Appendix: on working with a computer
I haven't done this sort of thing before and wondered if those atte