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Underpromotion is where the pawn reaches the 8th rank and promotes unexpectedly. It is similar to promotion, but underpromotion turns the pawn into Rook, Bishop, or Knight, instead of a Queen. Underpromotion is sometimes better than promoting to a Queen because in some situations, promotion to a Queen results in a stalemate. Here are some circumstances where underpromoting is necessary: 

  • The Knight has its own unique movement. No other chess pieces has the ability to move like a Knight. 
  • Promoting to a queen allows a stalemating combination.
a b c d e f g h
8 a8 b8 c8 d8 e8 f8 g8 h8 8
7 a7 b7 c7 d7 e7 f7 g7 h7 7
6 a6 b6 K c6 P d6 e6 f6 g6 h6 6
5 a5 b5 c5 d5 r e5 f5 g5 h5 5
4 a4 b4 c4 d4 e4 f4 g4 h4 4
3 a3 b3 c3 d3 e3 f3 g3 h3 3
2 a2 b2 c2 d2 e2 f2 g2 h2 2
1 a1 k b1 c1 d1 e1 f1 g1 h1 1
a b c d e f g h
Saavedra position

Here are a sample of chess moves in the game Saavedra, Fernando vs. Unknown player. 


/*99 times out of 100, such a position would be totally drawn. But the terribly awkward position of Black's rook gives White a golden opportunity. 1. c7 Had Black's rook been anywhere but d5, a move to the c-file or 8th rank would secure an immediate draw. As it stands, the rook must resort to a series of desperado checks. 1... Rd6+ 2. Kb5 The king must tread carefully. Both*/

(2. Kb7?? Rd7 and)

(2. Kc5?? Rd1 are to be avoided at all costs.)

2... Rd5+ 3. Kb4 The cat-and-mouse game continues. 3... Rd4+ 4. Kb3

(4. Kc3 leads to a transposition after 4... Rd1 5. Kc2 Rd4)

4.../* Rd3+ 5. Kc2 Black has finally run out of checks. High time, it would seem, to stop the clock and head to dinner. 5... Rd4! Not so fast! A keen tactical eye will quickly notice that 6.c8=Q allows 6...Rc4+!! 7.Qxc4, when the Black monarch is stalemated. Indeed, this position was thought to be drawn until Mr. Saavedra came around. In general terms, Black's king is abysmally situated, but after 6.c8=Q this lack of space is precisely what enables him to escape with a draw. There is seemingly no way around this irksome tactical quirk, unless of course... 6. c8=R!! Unless of course White doesn't promote to a queen! This incredible move, the quintessential example of underpromotion, has been published, analyzed, re-published, and re-analyzed by chess players and enthusiasts all over the world. The rook's inferiority works in White's favor, as 6...Rc4+ obviously loses its meaning. Black is therefore obliged to resort to passive defense.*/

(6. c8=Q?? Rc4+! 7. Qxc4)

6... /*Ra4 But now, with both of Black's pieces so vulnerable, it is no surprise that White has a deadly tactical shot at his disposal. 7. Kb3! Game over. There is no way to simultaneously defend the rook and parry the mate threat. 1-0*/

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