The Hardest chess problem in the world?

Hebden Bridge Chess Club members will be well acquainted with my passion for digging up chess curiosities from across the ‘interweb’. Recently I came across the perplexing puzzle below. It’s White to play and mate in 1.

White to play and mate in 1

Yes, in 1! Try putting that one through your computer and it will fry it’s chips before it finds the answer. If I told you that the solution is a VERY unusual move that is no longer strictly within the bounds of the rules of the game then that might help you a little bit. The solution will be revealed at the bottom of this post.

Anyway, the legend around this particular problem is shrouded in mystery. No-one knows who composed it, nor do they know when, but it is evident that this puzzle pre-dates the publication of FIDE’s official rules of the game (another little clue there).

As usual, I was not satisfied with this lack of provenance and so, having tried to cultivate a lead from the internet and failed, I turned to this blog’s old friend and oracle on chess history, the Duchess of Blunderboro, to see if she might be able to provide me with a clue. So, last week I sent her an instant message with the problem attached. Here is how our chat developed:

Intermezzo: Hi Duchess. Any idea who composed this problem?

Duchess: Oh yes! That one is one of Grand Fathers. It’s a funny story actually.

Intermezzo: Wow! Care to elaborate for me? How about a blog post?

Duchess: Certainly!

So, without further ado, I’ll hand over to the Duchess, who will explain all.

The Duchess of Blunderboro

“I first encountered this position in June 1937 and I was 15 years old. It was a warm summer’s day. I had taken my chess set out to the conservatory and was thumbing through one of my Grandfathers old score books in a bid to convince my Father that I was taking my chess education seriously. I had idly played through several games without taking too much time to consider the ideas behind the moves when I reached the final stages of the game in which the position in question appeared. Noticing that the game lasted only a few moves more I paused for a moment to visualise them as I couldn’t be bothered to play them out over the board. As I did this a voice from just behind me said “There’s an amusing story behind that position”.

Jumping with the shock of the sudden interruption, I turned to see that Daddy had sneaked up behind me and was smiling at the recollection of some long distant memory. “It looks like a perfectly straightforward position to me. Black should really have resigned long ago” I observed a little put out that I was being spied upon.

“I’d have to agree with you,” said my Father as he moved round the table to sit down opposite me. “But how about if I told you that Granddad had missed a very unusual and extremely witty mate in one in this very position?”

A cursory glance at the board told me that there was no such mate in one. “Impossible!” I announced. There is no way for White to mate in one move, even by some such sneaky means as an under promotion.”

“Again, I agree with you,” my Father beamed back, “and so did Granddad. But when you’ve been told that there is a mate in one by non-other than the great Adolf Anderrsen, you have to take it seriously.”

“What? “ I spluttered. “Anderssen saw this game and found mate in one?”


The Cafe de la Regence


“Indeed he did,” confirmed my Father. “Your Granddad played this game in Paris at the Café de la Regence in 1878. It was a casual game against a fellow of no particular consequence but, as was his habit in those days, he recorded the score so that he could study the game at a later date. It just so happened that there was a big international tournament taking place in Paris at that time and consequently several of the world’s best were taking their leisure in the café which was renowned as a venue for chess playing. Anderssen, who was nearly 60 years old at that point and competing in what turned out to be his last tournament, happened to be one of small group kibitzing Granddad’s game right at it’s very end and had had a joke with him at it’s conclusion saying

Adolf Anderssen in later life

“Did you know that you missed a very amusing check mate in one a couple of moves before the end?”

Your Granddad had been dumbstruck as he well knew who Anderssen was but was totally convinced that no such mate existed so he didn’t know how to respond. Anderssen had quickly set up the crucial position on the board again and then said.

“The solution really is most unusual. In fact I’d say it would make a striking problem. Check mate in one move. Can you find it?”

Your Granddad told me that he, his opponent and the growing group of kibitzers stared in stunned silence for a couple of minutes trying to find the answer. After a while it became evident that they couldn’t do it so, quietly, Anderssen reached across the board and pushed the White pawn to b8. He then picked it up and replaced with… a black knight!”

As he said these words my Father replicated the great man’s actions, under promoting the pawn to a black knight. He chuckled merrily as he did so. I starred open mouthed in amazement for it was, undeniably, checkmate.

1. b8=N (black) and check mate!

“But, surely that’s illegal,” I stammered.



“Yet again, I must agree with you,” laughed my Father. “But in fact, at the time this game was played there was no specific rule stating that a pawn had to be promoted to a piece of the same colour!”

So, this then is the story behind the position which has since become known a chess problem of unknown origin. For myself I like to think that the origin was Anderssen himself for he was a renowned composer to chess problems and had said himself that the position would have made a striking puzzle. Being as he died not long after the Paris tournament I often imagine that this position might have been found amongst his documents after he died unpublished and uncredited. This is fanciful of me perhaps, but it's plausible.”

Thanks, as ever, go to the Duchess for bringing us this 'exclusive' story. As a final note on this, the hardest of chess problems, I should add that FIDE’s official rules require that a pawn on the eighth rank must promote to a piece of the same colour