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When you have opened a file alongside your opponent's king, and are barging ahead with a mating attack using your major pieces, it is a lesson most of us learn from bitter experience that rooks should lead the way with a queen in the rear, rather than the other way round. This is a theme problemists have put to good use too. Take the following position, for example. Composed by Eric Zepler in 1933, it is White to play and mate in four.

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,G, , ,

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, , , ,

, , , ,

,H,S, ,

ANf, , ,

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1.Rc7?? is stalemate, 1.Rd7? loses the queen to Nb4+, and 1.Qe2 invites 1...Nb4+! when Rxb4 is stalemate again. The natural try is something like 1.Qd6 followed by Rd7 and Qd1 mate, but Black plays 1...Ne1! 2.Rd7 Nd3! when 3.Qxd3 is stalemate again.

That last variation (particularly when taken in conjunction with the opening comments) should suggest the right answer: 1.Qd8! Ne1 (best) 2.Rd7! and now 2...Kc2 3.Rd1! forces a knight move when Qd3 (or Qxd3) is mate, while 2...Nd3 3.Rxd3! Kc2 allows 4.Rc3 mate.

The next diagram is a far more complex and beautiful version of the same theme. It is White to play and mate in 7 and was composed by Markus Ott in 1959.

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n , n ,

,h, nH,

, ,A, ,

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dn NH, ,

zf,S, ,G

With Black's king entrenched in the corner, it is not easy to see how White will get at it, even with seven moves to spare. One try might be to bring the king closer, but 1.Kd3 e4+ 2.Kc2 b4 even leaves Black threatening b3 mate.

Another idea is to wait for b4, then play Qa4 followed by Rxb1+ when Kxb1 is met by Qd1 mate. But after 1.(something) b4 2.Qa4 b3! where does White go?

The formula has to be (White moves indicated by question marks): 1.?? b4 2.Qa4

b3 3.?? b5 4.?? b4 and then a brilliant three-move mate. If only White's queen and rook were the other way round, we might have a glimmer of an idea. Okay, lets do it: 1.Rf1!! b4 2.Qa4 b3 3.Qa7!! b5 4.Qg1! b4 and now the clever bit: 5.Rxb1+! Bxb1 6.d3!! Ka2 7.Qa7 mate! Finally, if Black meets 1.Rf1 with Bd5+, White mates with 2.Kxd5 Ka2 3.Qxb1+ Ka3 (or Kb3) 4.Rf3+! Ka4 (or Kb4) 5.Qe4+ Ka5 6.Ra3. The fourth move of that line explains why 1.Re1 does not work in the starting position.

William Hartston