The Rarest Chess Move: Underpromoting To A Bishop!
Underpromoting to a bishop must be the rarest move in chess. We can easily think of some famous examples of rook promotions (such as the brilliant Saavedra study), and by comparison knight underpromotions happen every day - just think of this opening trap in the Albin Countergambit.
Bishop underpromotions are however nearly unheard of in practical play. Sure, you can easily find some examples of players showing off (for example, Rybka vs. Hikaru Nakamura), but why would you NEED to promote to a bishop.
The answer is almost always "to avoid stalemate." Even though I think that stalemate is a rubbish rule , it is the law of the land, and a stronger side may fairly often not be able to promote to a queen or a rook without allowing this narrow escape.
In practical play, I am only aware of TWO examples where promoting to a bishop was the correct and ONLY winning move. Here they both are:
Reshko vs. Kaminsky, 1972
Kholmov vs. Ehlvest, 1983
The following brilliant study certainly SEEMS like it could have occurred in practical play, but I've never seen proof that it has, although I consider it one of my favorite studies of all time and the absolute best example of a bishop promotion in chess.
Dehler, 1921 (Thanks to @jdcannon for helping me find this!)
There are lots of other great bishop promotions in composed positions (like this beautiful thinkpiece from GM David Smerdon), and there have been other sensible and clever bishop underpromotions like the following two positions (both from Tim Krabbe's fantastic blog on underpromotion), though in my opinion, it seems neither was quite the "only winning move" in a strict sense.
Boniface vs. Pugh, 1995
Sokolsky vs. Ravinsky, 1938
Have I missed some great bishop underpromotions? If so, share your favorites in the comments!
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