White would love to play 23 Qh6 followed by 24 Qg7#, but black would spoil that plan by playing 23...Qxh3+.

So, how does white keep his options open, but stop black's plans in their tracks? With...

23 Rf5

The rook acts as a blockade on the c8-h3 diagonal, and it cannot be taken using the pawn, eg: 23...gxf5 24 Qg5+ Kh8 25 Qg7#.

So, what does black do? Probably resign. White will play 24 Qh6 next move and the only way to slow white down is capture the pawn on f6, giving up a whole queen.

Time to check and see how this played out.

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First I thought about moves like Kg1, but this allows Black to organize a defense.

So something more forcing is requested.

23. Rf5! and White treat is covered without time for Black to organize the defense. eg.

After not seeing any results from 23.Ng5 or 23.Qh6 (which is in fact dangerous and possibly leads into a draw), the right move snapped on me:

23.Rf5
This move closes the diagonal occupied by Black Queen and the Queen can not capture it because it is supported by e4 pawn or at the most can capture it but loose the Queen.

White to play (23.?) "Medium", White is up a pawn.

Black is threatening 23...Qxh3+, so White obviously has no time for 23. Qh6 Qxh3+ 24. Kg1 Qxg3+ with a draw. Also, 23. Ng1 gives Black time for 23...Kh8 24. Qh6 Rg8 and White's knight is two moves away from playing Ng5, so retreating leaves something to be desired. White needs a bolder plan.

23. Rf5! Kh8

There is nothing better; if 23...gxf5 24. Qg5+ Kh8 25. Qg7#.

24. Qh6 Rg8 25. Ng5 and mate next move.

First impression:

Main idea has to be to <cut off the Black Q's> killing sight on h3 or cater to cover it.

Candidates.

i) N move, to g5. Defensive. It forces a decision on the Black Q; a retrograde return to base. But does not move White's attack portfolio.

ii) Q to h6? Can only be a wish in view of a very sore h3.

iii) Can the R to f5 be a candidate? Yes; not even the 'g' P can take it. Very promising, cuts off the Black Q and opens an excellent vista to the White Q.

Black cannot afford to capture it with the 'g' P as that opens even g5 for the Q. Black's options? Only one, K to h8. I can see game over.

The obituary;

<23. Rf5 Kh8 24. Qh6 Rg8 (a death pang) 25. Ng5>; 1-0 without an actual check or bloodshed.

click for larger view

Checking up is really superfluous, 'cept for a spoiler.

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And today's little gem is ... shooting your own guys. There are two variations of this theme. The first is the really evil baddie who shoots his own soldier through callousness. The second is the heroic commander who is forced to kill a colleague because their really is no choice. The difference is that the baddie doesn't flinch. The hero agonises about it over and over again.

Examples? For the baddies we have Darth Vader force-strangling a death star officer. Die Hard 2 (replace the tower block with an airport). The orcs in Lord of the Rings. Just about any german officer in WW2 films. A normal day in the office for Ming the Merciless.

For the good guys ... almost any film set on a submarine. At some point someone is going to have to seal off a compartment which is flooding. But his own men are inside! Oh, the horror, dilemna, the struggle, the humanity of it all...

Chess doesn't work that way. We can send our own men forwards to be killed by the enemy, but we absolutely cannot kill them ourselves. And that can give rise to some frustrating situations. Take today's POTD a couple of moves earlier than the puzzle position:

click for larger view

White would love to play 22. Qh6, but his own knight is in the way. In an ideal world we would love to flood the compartment by turning one of those wheely things on the ceiling. I've always wondered, by the way, why submarine commanders don't go round and twiddle all of those wheels before the battle starts. It always seems to turn the water off, so why not leave them turned off permanently?

Then we have our puzzle. With 23. Rf5 we offer up the rook. If black retakes with 23...gxf5 his own pawn blocks his queen's attack on h3. He'd love to whip out a pistol and shoot his pawn, but that's against the rules, dear boy. Not cricket.

Finally we get to the finality that is ultimately called the final position:

click for larger view

White is a pawn up with a strong position, but he does not have time for 23. Qh6 because of 23...Qxh3+. My first candidates involve moving the knight:

23. Nf4 Qxf6 and there is no good follow-up for White, as his knight is pinned against the Rf1.

23. Ng5 Qe5 and the Knight has blocked the Queen's route to h6, which seems undesirable.

23. Ng1, threatening 24. Qh6 looks strong, but Black can defend with 23...Kh8 24. Qh6 Rg8

So, lets look for some other way to stop Black from captureing the Knight while allowing White's queen access to h6.

Aha!

23. Rf5 Kh8 (23...gxf5 24. Qh5+ Kh8 25. Qg7#) 24. Qh6 Rg8 25. Ng5

and mate is inevitable.

1) "Captureing" is of course "capturing" (slightly embarrassing for someone with a BA in English Literature, an MA in Applied Linguistics and an almost-finished novel in my top drawer).

Black threatens 23... Qxh3+ which leads to perpetual if White plays 23.Qh6.