Saavedra position

The Saavedra position is a composed study with only four pieces: White king and pawn against Black king and rook. A study is a constructed position designed to contain a unique or especially instructive solution. Although the rook appears able to stop the pawn, White wins by calculating both the checks and the choice of promotion piece.

When a pawn reaches the last rank, it may become a queen, rook, bishop, or knight. Choosing a queen is normal, but it fails here. In algebraic notation, which names every square by file and rank, c8=Q means that the pawn reaches c8 and becomes a queen. The ? sign marks the move as a mistake. After 6.c8=Q? Black has 6...Rc4+, and 7.Qxc4 is stalemate because the black king is not in check and has no legal move.

The solution is 6.c8=R, promotion to a rook. This preserves the win without allowing the same stalemate trap. After 6...Ra4 7.Kb3, the black rook cannot survive White's threats. The lesson is not to choose a weaker piece for spectacle, but to compare which legal replies each promotion leaves the opponent.

Fernando Saavedra found this possibility in 1895 after the position had been presented as a draw. The study became a classic example of underpromotion, the name for promotion to any piece other than a queen.