Pawn breakthrough

A breakthrough is a pawn sacrifice that creates a passed pawn. In the three-against-three pattern below, White plays b6 and then a6. After Black takes both times, the c-pawn is passed.

1. The pattern needs a pawn majority that can trade in the right order, or a wedge where one capture opens a file for a different pawn.
2. Count the race after the trades. A breakthrough that promotes one move after the opponent promotes is only a draw if the new queens can hold, and a loss if they cannot.
3. The king being far away is the usual setting. If the kings are close, the sacrifice may simply lose a pawn.
4. Passed pawns in the puzzle set are the practical version of this idea.

On the board