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151. Thomas Denton Clarke
The Illustrated London News 1908
Mate in 3

The black king has access to two flights, providing for which turns out to be impossible for White. So the key must aggressively eliminate them, but 1.h8(Q)? with the threat of 2.Qf6 and 3.Qxf4 fails to 1…c5!, when stalemate looms. Instead the key is 1.h8(B)! (waiting), and if 1…c5 then White exploits Black’s lack of mobility with 2.Bf6 Kf5 3.Bd3. The other two pawn defences bring about a nice change of promotion by the e7-pawn: 1…c6 2.e8(Q) c5 3.Qa8 and 1…cxd6 2.e8(S) d5 3.Sd6.

 
152. Arthur Mosely
Northern Whig 1912
1st Prize
Mate in 2

The brilliant key 1.Se4! (threat: 2.Re8) sacrifices the knight to eight black pieces, with each ensuing capture leading to a different mate. 1…Kxe4 2.Re8, 1…Qxe4 2.Qh8, 1…Rxe4 Qxf5, 1…Bxe4 2.d4, 1…Scxe4 2.Rxd5, 1…Sfxe4 2.Sxd3, 1…dxe4 2.Bd4, and 1…fxe4 2.Qe6. The eight-fold sacrifice of the key-piece constitutes a record, and it is achieved in an attractive setting with ideal black economy – every black piece on the board takes part in the thematic play. Another two-mover manages to show nine sacrifices of the key-piece but it requires the first move to be a check.

 
153. Frederick Hawes
The Australasian 1913
1st Hon. Mention
Mate in 2

Only one black move in the diagram, 1…Rb4, has not been given a set mate, and the key 1.Bb5! (waiting) completes the block by providing for it. A Grimshaw interference occurs on b4: 1…Rb4 2.c6 and 1…Bb4 2.Rc4. These two defences are actually correction moves that prevent the mates following the ‘random’ move of each black piece, 1…Ra~ 2.Rc4 and 1…Ba~ 2.c6. Another correction move is 1…Bxc5+, enabling 2.Qxc5. A second Grimshaw takes place on g6: 1…Rg6 2.Sf5 and 1…Bg6 2.Sh7, though here only the bishop has a random defence, 1…Bh~ 2.Sf5. The other rook move, 1…Rxf6+, allows 2.Bxf6. Also, 1…S~ 2.Rd2, and 1…e3 2.Sf3.

 
154. Terence Gallery
The Tablet 1948
Mate in 3

A nondescript key 1.Rc2! waits for Black to play the only legal move, 1…c4, whereupon the rook makes a surprising sidestep 2.Rb2 to grant a flight. Two sub-variations follow with 2…Kc3 3.Bg7 and 2…c3 3.Rb4. A pleasant miniature even if the amount of play is limited.

 
155. Peter Wong
British Chess Magazine 1996
2nd-6th Place =
Shortest proof game in 15½

The game blends two paradoxical themes: black pseudo-castling that’s motivated by tempo loss, and a white queen Pronkin. 1.a4 h5 2.a5 h4 3.Ra4 h3 4.Rh4 Sh6 5.e4 Sf5 6.Qf3 Sd6 7.Qf6 gxf6 8.Se2 Bh6 9.Sec3 Be3 10.f4 Bb6 11.axb6 Kf8! 12.bxc7 Kg7 13.cxd8(Q) Rf8 14.Qa5 Kg8 15.Qh5 Sb5 16.Qd1. Black avoids castling at move 11 because afterwards neither the king nor the rook would be able to lose a tempo, e.g. 11…0-0? 12.bxc7 Kg7 13.cxd8(Q) Kg8 14.Qa5 Kg7 15.Qh5 Kg8 16.Qd1 Sb5 – a single move too long. The Pronkin theme is shown in that the white queen, seemingly on its original square, is in fact a substitute promoted piece.

 
156. Herbert Grant
Australian Columns Tourney 1924
1st Prize
Mate in 2

Three set variations cover every possible black move in the diagram: 1…Sd~ 2.Bb2, 1…Se~ 2.Qc2, and 1…c3 2.Sb3. Simple waiting moves would fail, e.g. 1.Kh1? Sf2+!, and 1.Qg6? Sf5! The nice withdrawal key 1.Qb7! (waiting) shifts the direction from which the queen controls b1, resulting in a complete change of play: 1…Sd~ 2.Qb2, 1…Se~ 2.Rc2, and 1…c3 2.Sd3. Another gem of a mutate.

 
157. Laurie Hill
Chess in Australia 1975
1st Place
Mate in 3

A good sacrificial key 1.Sxe6! threatens 2.Sxc7+Rxc7 3.Re5. Six thematic variations follow, each one utilising the b3-bishop and c4-knight to arrange a Siers battery. In this manoeuvre, White moves the front piece of the battery (the knight) to give a discovered check, and forces the black king to a flight-square (e5), after which the front piece moves again to mate from another direction. 1…Bxe6 2.Se3+ Ke5 3.Sg4, 1…Rxe6 (or 1…Rxb5) 2.Sa5+ Ke5 3.Sc6, and 1…Qxe6 2.Sd6+ Ke5 3.Sf7 – these lines are especially interesting in that White exploits Black’s self-pins on the e-file. 1…Sxe6/Sfg6 2.Sxb6+ Ke5 3.Sxd7, 1…Rxe7 2.Sb2+ Ke5 3.Sd3, and 1…Sf3/Shg6 2.Sd2+ Ke5 3.Sf3. “Outstanding,” said the late great William Whyatt who judged the tourney.

 
158. Joseph Heydon
Australasian Chess Magazine 1919
Mate in 2

The key 1.Be1! threatens 2.Bf2. Black has four defences that unpin the white queen, and the resulting queen mates are skilfully differentiated: 1…Sc6 2.Qc4, 1…Sd5 2.Qd4, 1…Rd5 2.Qb4, and 1…f3 2.Qxe7. There’s by-play with 1…axb5 2.Bb4, 1…Bxe4+ 2.Sxe4, and 1…Se6 2.Sd7. This problem makes an interesting comparison with No.150, which shows the white queen unpinned on an orthogonal line. Heydon’s position here is heavier but presents a more impressive seven variations.

 
159. Gordon Stuart Green
Source?
Mate in 4

White begins with 1.Bg1!, shifting the bishop across f2 to prepare for a self-interference on that square. If Black aims for stalemate immediately with 1…h5, then 2.Sf2 Kc5 3.Se4+ Kxd5 4.Sxc3, or 3…Kb4 4.Bc5. If Black plays 1…h6 instead, White has time for another critical move, 2.Ra8, crossing over a7. Now 2…h5 is answered by 3.Ba7 – a self-interfering move that’s also a switchback – Ka5/Ka4/Ka3 4.Bc5.

 
160. Laimons Mangalis
American Chess Bulletin 1962
1st Hon. Mention
Mate in 2

Since 1.Rb5+? permits 1…Kc4!, the white bishop attempts various anti-critical moves that cross over b5 and thus avoid the self-interference. Three such tries threatening 2.Rb5 are defeated, however, when the bishop closes a line needed by the white queen: 1.Bd3? 1…Ra5 2.Qxg1, 1…Rb6 2.Qxh5, but 1…Qe8! 1.Be2? 1…Qe8 2.Qd5, 1…Ra5 2.Qxg1, but 1…Rb6! 1.Bf1? 1…Rb6 2.Qxh5, 1…Qe8 2.Qd5, but 1…Ra5! (Also, 1…c6 2.Sb7 after each try.) The key 1.Bb5! surprisingly creates a new threat of 2.Sb7, and following similar black defences the queen is able to mate unhindered: 1…Ra7 2.Qxg1, 1…Rb6 2.Qxh5, and 1…Qd5 2.Qxd5.

 
161. Dennis K. Hale
Chess in Australia 1977
“Vanishing Trick”
In which of these positions could
the black king have moved last?
(a) The diagram
(b) Remove the f2-pawn

In the diagram position, if the black king had moved last, it did not come from e7 or f7, since on either square the piece would have been in an impossible double-check. If the king just came from f6, it would have been in check from both the a1-bishop and f4-rook, and that’s possible only if the king had captured a pawn on e6, which had delivered the double-check with an en passant capture. So let’s retract 1…Kf6xPe6 2.f5xe6 e.p.+ e7-e5, leading to a position where the king on f6 is in check from the a1-bishop. White could have given this check only by discovery, using the white king. But if we further retract 3.Kd4-e4+, the white king would have been in an impossible check from the e3-bishop, since there’s no square from which the black piece could have played from. Given that no more legal retractions are possible, we have proved that the black king couldn’t have moved last in the diagram. In position (b) without the f2-pawn, however, the same sequence of retractions – 1…Kf6xPe6 2.f5xe6 e.p.+ e7-e5 3.Kd4-e4+ – becomes viable, because now the black bishop could have checked by capturing on e3 from f2 or g1. Thus the black king could have played last in (b).

 
162. Brian Tomson
Chess in Australia 1977
1st-2nd Hon. Mention =
Mate in 2

Most of Black’s moves have been provided with set mates, including 1…Sa~ 2.Qc5 and 1…Sg~ 2.Qh2. The exception is 1…Sf4! which would defeat a simple waiting move, such as 1.Kb6? The try 1.Qc1? (waiting) changes one variation to 1…Sg~ 2.Qf4, but 1…Se3! refutes. The key 1.Qd2! (waiting) produces another change, 1…Sa~ 2.Qb4, with an added line, 1…Sc5+ 2.dxc5. A random move by the other knight now allows a dual, 1…Sg~ 2.Qh2/Qf4, but these mates are separated with 1…Se3 2.Qh2 and 1…Sf4 2.Qxf4. The black rook gives three dual-free variations: 1…Re6/Rf8 2.Re6, 1…Rf7+/Rxg6 2.Sf7, and 1…Rxf5 2.Sxf5.

 
163. Ernest Jerrard
The Brisbane Courier 1920
1st Prize
Mate in 2

A good key 1.Kg5! (threat: 2.Sf6) permits three black checks, but the best variations are 1…Rd3 2.Bb3 and 1…Rxd4 2.Bc4. In both cases the black rook defends by creating a flight (on e3 and e5 respectively), but these moves also self-block, enabling the white bishop to fire the battery and self-interfere on a line of guard with impunity. The battery fires again in response to two checks, 1…Qd5+ 2.Bf5 and 1…Sxf7+ 2.Bxf7, while the third check 1…Rxg3+ is answered by 2.Sxg3.

 
164. William James Smith &
John James O’Keefe
The Brisbane Courier 1917
4th Prize
Mate in 2

All black moves are given set mates in the diagram. In particular, the black queen cannot move without allowing at least one of three mates on a3, e3, and c5. Some waiting move tries are 1.Rg4? Qc5!, 1.Rh5? Qg1+!, 1.Kh8? Qd4+!, and 1.Bf6? Qd4! The key 1.Rg3! (waiting) sets up an indirect battery on the third rank, so as to answer 1…Qc5 with 2.Sb2 (instead of the set 2.Rxc5). 1…Q~ 2.Sa3 or 2.Se3, 1…Ba6/Ba4 2.Sa3, 1…S~ 2.Rb4, and 1…f6/f7 2.Qe6. A mutate with one excellent change of mate.

 
165. Ian Shanahan
The Problemist 2004
Helpmate in 3
2 solutions

The two harmonious solutions show an orthogonal-diagonal transformation: 1.d2 Bb1 2.Qc2 Rxc5+ 3.Kd3 Bxc2 and 1.Rc6 Ra5 2.Qb5 Bxd3+ 3.Kc5 Rxb5. In each phase, Black opens a line that is traversed by two different coloured pieces following one another – the latter manoeuvre is known as a mixed Bristol. The black king then occupies a square that has just been passed over by the two pieces (the same square vacated by Black’s initial move). Finally the white Bristol piece captures the black one to give a model mate.

 
166. Molham Hassan
Australasian Chess 2012
Mate in 2

White starts with 1.Bc6! to threaten 2.Ba4. The black knight has three defences that yield different mates: 1…Sc5 loses control of the R + B battery, allowing 2.Bc1; the self-block 1…Sxb4 enables the Q + R battery to fire with 2.Rc3; and 1…Sxb2 self-pins, admitting 2.Qxe3. One more variation is 1…Be8 2.Re4, another battery opening. A cleanly constructed problem with no pawns.

 
167. R. F. Fegan
The Guardian 1962
2nd Commendation
Mate in 3

The clearance key 1.Bh7! (waiting) prepares for 1…axb2 2.Qg6 with the threat of 3.Qb1 – this illustrates the Turton manoeuvre (the queen steps into and then moves along the line traversed by the bishop, in the opposite direction) – 2…Ra6 3.Qxa6. Two more captures on b2 generate the variations 1…Kxb2 2.Qxc4 (waiting) Ra1 3.Qc2 or 2…Ka1 3.Qc1, and 1…Rxb2 2.Qxa3+ Ra2 3.Qc1. Also, 1…c3 2.Qf1+ Kxb2 3.Qb1. Plenty of varied play for a problem with only eight pieces.

 
168. Andy Sag
OzProblems.com 2014
Mate in 2

Two black defences have set dual mates: 1…b2 2.Bb3/Bh7 and 1…exf2+ 2.Qxf2/Rxf2. The sacrificial key 1.Sd3! (waiting) removes an unprovided flight on b2 but grants a new one on d3. Accepting the sacrifice induces a castling mate: 1…Kxd3 2.0-0-0. The other lines are 1…b2 2.Sb4 (changed play), 1…exf2+ 2.Qxf2 (dual eliminated) and 1…e2 2.Rc1.

Nigel Nettheim: If the solver is aware of the impending castling, this will be easy to solve; otherwise, it would no doubt be harder. The g1-queen would have been replaced by an f1-rook if three white rooks were tolerated. Finally, when there are 8-12 units on the board solvers are of course in duty bound to drop in the word “Meredith”.
Gary Simms: My first thought was 1.Qh1, looking at the h7 check, but quickly saw that the king having the b2 escape square spoiled any thoughts like that. Then I zeroed in on solving the b2 problem and decided 1.Sd3 was the only reasonable way to stop that up. I’m surprised the location of the king and rook didn’t tip me off sooner to the castling mate. Very nice.

 
169. Matthew Fox
The Australasian Chess Review 1940
Mate in 2

After the key 1.Sb5!, White threatens 2.Sxd4. The g7-knight has two defences, both interfering with the black queen: 1…Sf5 2.Qh1 and 1…Se6 2.Rd6. The former variation illustrates an idea called Gamage unpin – a black self-interference enables White’s mating move to unpin a black piece (the queen), which otherwise would have prevented the mate. The g5-rook produces three lines of play: 1…Rg6/Rg4 2.Qc1, 1…Rxb5+ 2.axb5, and 1…Rd5 2.Rc7. Lastly, 1…Qd6+ permits 2.Rxd6/Qxd6.

Nigel Nettheim: Very nice, especially 1…Sf5 2.Qh1. There is a rather unimportant dual after 1...Qd6+. I’m not sure why the e7-rook has been used instead of a c8-bishop.

Indeed, computer-testing confirms that the problem’s economy can be improved in a couple of ways. Besides replacing the rook with a white bishop on c8, we can also use a black rook on f6 instead of the queen. This means the threat of 2.Sxd4 is no longer a pin-mate, but the solution is not affected, except for a slight improvement in removing 1…Rg6 as a defence that would allow the same mate as 1…Rg4. Furthermore, the placing of the c8-bishop makes me wonder if 2.Bb7 mate could be worked into the position as an extra variation. This is in fact possible, and the setting below is the most economical way I could find to do it.

169b. Matthew Fox
The Australasian Chess Review 1940
Version by Peter Wong
Mate in 2

Hence after 1.Sb5!, the self-block 1…Sxd7 enables 2.Bb7. A disadvantage of the new version is that 1…Sxd7, being such a strong defence, makes the key easier to spot. But overall I think it’s worthwhile to add another variation to the problem when we actually save on the number of pieces used.

 
170. H. Cox
Chess World 1947
Mate in 2

The diagram position is a complete block, with all black moves allowing immediate mates: 1…Sd~ 2.Re6 and 1…Sb~ 2.Rc5. But the set play cannot be maintained, and White’s key 1.Sf2! (waiting) changes both responses to the black defences: 1…Sd~ 2.Qe4 and 1…Sb~ 2.Qxd6. So a pair of rook mates is switched to a pair of queen mates. The fine key also grants a flight to give an added mate, 1…Kf4 2.Qe3. The try 1.Sg5? would yield similar changed play but not provide for 1…Kf4!

Nigel Nettheim: An elegant change-mate problem. There is nothing I can add, because “all change here” (taken from an announcement used in the British rail system) has been said more than enough times already!

 
171. William J. McArthur
The British Chess Magazine 1881
Version
Mate in 3

The give-and-take key 1.Be3! entails a short threat, 2.Qf3. If 1…Kxe3 then 2.Qxb4 forcing 2…Ke2 3.Qe1. If 1…Kd5 then 2.Qf7+ leading to 2…Kd6 3.Qd7 or 2…Ke4 3.Qf3. The first two mating configurations are charming chameleon echoes. The original version of the problem has a white pawn on c6 instead of the black pawn on b7 (either pawn prevents a ruinous dual, 1…Kd5 2.Qf6 threatening 3.Qc6). But such a white pawn would guard the mating queen on d7 in the second main variation; the e5-knight is thus made redundant in the final position and the echo mates become less convincing.

 
172. Andy Sag
OzProblems.com 2014
Mate in 2

Three close tries are 1.Rcb8? (threat: 2.Rxb6) a3!, 1.Qe4? (2.Qd5/Qe5) a3!, and 1.Qg8? (2.Qd5/Qxc4) Sf5+! The set variation 1…c3 2.Qd3 is discarded by the sacrificial key 1.Qd3!, which threatens 2.Qxc4. 1…cxd3 activates the white pawn to mate on the same square as the threat: 2.c4. The black knight has two defences that provoke a pair of queen mates: 1…Sc6 2.Qd5 and 1…Sf5+ 2.Sxf5. Finally, 1…bxa5 opens the b-file for 2.Rcb8.

Nigel Nettheim: 1.Qd3! is a brilliant key. A number of tries, though 1…a3 is a strong defence.

 
173. Rowland Bain
Chess in Australia 1985
Mate in 2

A nice key, 1.Sc3!, concedes a flight on d4 and threatens 2.Qxb4. A ‘random’ move by the b4-knight, 1…S~, opens the b-file and permits 2.Qb6. The correction move 1…Sd5!? prevents 2.Qb6 but commits a new error of self-block, allowing the c3-knight to interfere with the g2-bishop: 2.Se4. Taking the flight does not disable the threat: 1…Kd4 2.Qxb4, while capturing the key-piece gives 1…Bxc3 2.Qxc3. Another self-blocking variation is 1…Rd4 2.Rb5, and if 1…Ra4 then 2.Sxa4. This problem competed in a tourney for pawnless positions, and the judge Alex Goldstein commented that it was “a clear candidate for the prizes… but the dual 1…Sa6 2.Qb6 or 2.Sa4 ruined its chances”.

 
174. James Joseph Glynn
The Week 1879
Mate in 3

Black has just one legal move in the diagram, and surprisingly the only way to deal with it is 1.Rg7! (waiting), which gives the black king two more flights. 1…Kc4 is met by 2.Rg2 Kd3 3.Qd4. If 1…Ke4 then 2.Qe2 forces 2…Kxf5 3.Qf3. And 1…Kxe3 enables 2.Rg3+ Ke4/Kf4 3.Qe5. A pleasant miniature displaying a variety of mating nets.

 
175. Alexander Goldstein
The Problemist 1977
Mate in 2

The key 1.Rf6! threatens 2.Rf4 (not 1.Rg6? because of 1…Bh3!). The half-pin arrangement on the fourth rank means that when either Black’s queen or rook moves off the line, the other becomes pinned – a weakness that White exploits in the mate. 1…Qxa6 2.Qxb2, 1…Qc6 2.Sb3, and 1…Rb6 2.Qc5. Appropriately, the three thematic defences all pin the white rook, adding to the unity of the variations. Two secondary lines of play are 1…Qxd3 2.Qxd3 and 1…f2 2.Se2.

Dennis Hale: I certainly enjoyed the problem with its half-pin feature. The two queen defences and the one rook defence each self-pin and pin – I like the way the three associated white mating moves are differentiated. The key is not one of the problem's strengths. The squares e3, e4, and e5 in the black king’s field are each doubly attacked, and this tends to suggest the key is a move by the e6-rook.