# The Slaughterhouse

I made this problem with three Black pieces against the entire White army. I aptly named it "The Slaughterhouse" for a reason.

It's Black to move and selfmate themselves in 17 moves. Naturally, White chooses to delay the selfmate for as long as possible

Can you find the tactic that is required to solve this problem? I would also like a small explanation of why you choose the moves that you do.

• I can win as black. Jun 28 '19 at 12:42
• Can’t you still win as black, with 1. ... Bg3+ 2. Kg1 Qh2#? Interesting self-mate puzzle... Jun 28 '19 at 13:10

I spot a

windmill! 1 ...Bxg3+ 2 Kg1 Bh2+ 3 Kh1 Bxf4+ 4 Kg1 Bh2+ 5 Kh1 Bxe5+ 6 Kg1 Bh2+ 7 Kh1 Bxd6+ 8 Kg1 Bh2+ 9 Kh1 Bxc7+ 10 Kg1 Bh2+ 11 Kh1 Bxb8+ 12 Kg1

after which Black changes tack:

12 ... Bxa7+ 13 Nc5 (best) Bxc5+ 14 Rd4 (best) Bxd4 15 Be3 Bxe3 16 Rf2+ Bxf2+ 17 Qxf2# Even after all the pawns on the g3-c7 diagonal are gone, White still guards every square on the b6-f2 diagonal, so Black has no short cut: Black's bishop must operate the windmill all the way out to b8 so that it can get to the safe square a7.

What a slaughterhouse indeed! Well done!

As requested: an explanation of why I chose the moves I did. With such a terrifyingly long selfmate I thought that for the setter to have composed it at all, the solution must surely be a simple one, with Black always making checks which White can parry only in one way. I saw that most of them put a Black piece en prise -- not a good sign.

1 Bxg3+

looked better. Though it seems to be en prise, it isn't really, because White is in check from the other piece, and capturing the discoverer is not enough to get out of discovered check. From there it was no great leap of imagination to spot the idea that drives Black's play in the first part of the solution. The long diagonal of pawns with the bishop at one end was another clue.

I must admit that I underestimated the scale of the slaughter. I wondered if Black, after capturing the f4 pawn, could check with the queen so as to force White's queen or rook down for the mate. But that didn't work.

• I would also like to know exactly why you would choose a Windmill for a solution to Black's plan for a selfmate! Jun 28 '19 at 16:51
• Actually that went different from how I expected at first, from Black's 7th on. I thought that it would be enough to clear the f-file then play Black's Q to that file for the check that forces White's mate. But wow, what a slaughter. Great selfmate. Jun 28 '19 at 17:16
• If you like this sort of thing, here is another example. Jun 28 '19 at 17:41
• Thanks Rosie F.! It is a Saughterhouse indeed! Before I accept your answer though, please give my a small explanation as to why Black chose the tatics that chose! Jun 28 '19 at 19:04
• And thanks again for that Shable example! I tried searching K='Windmill' but that didn't work. I couldn't find a selfmate windmill anywhere so I decided to create one myself! It took some trial and error to create a flawless one. The tricky part was making sure that the pieces that move in the Bishop's path aren't protected! An 18-mover, although theorcitally possible within this idea, is still elusve to me... Jun 28 '19 at 19:10