When a pawn reaches the last rank it creates one of the biggest miracles of the game of chess. In such a situation the weakest chess piece can instantly become the strongest one! While in the majority of such cases, chess players indeed promote a pawn into a queen, sometimes another piece get chosen.
Let's discuss the different reasons you might prefer to promote your pawn into a piece other than a queen.
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- Combinations
In the majority of the cases when underpromotion is a part of a combination, a pawn gets promoted into a knight to deliver a deadly check. The following position is one of the first cases of a combination with underpromotion that I learned. Can you find the solution?
Mostly, combinations like this happen in endgames, but sometimes you can underpromote your pawn even in an opening:
When we talk about underpromotion into a knight with check, it is impossible to omit the following game where we can witness the almost problem-like excelsior.
- Defense
A less common case of underpromotion happens when you need to do it for defense. In such a case you always promote a pawn into a knight. Indeed, why would you promote a pawn into a rook or a bishop if a queen combines the abilities of both of them!
In the following game a promotion into a knight helps to shield white king against checks.
The same underpromotion into a knight is the only way to defend a theoretical endgame K+R vs. K+pawn:
It is also very common trick to underpromote into a knight to defend against a knight fork by your opponent. In the next game it happened two times!
- Stalemate prevention
The most common case of underpromotion into a rook is to avoid a stalemate. It happened in one of my games where unfortunately I was on the receiving end of the underpromotion.
My only consolation is that according to Tim Crabbe, this is the only known game with five rooks on the board!
Promoting a pawn into a bishop usually serves the same goal:
Next week we will analyze more amazing underpromotions.