In an informal game played between rounds at a tournament in London, Adolf Anderssen — playing White — pulled off the most audacious sacrifice sequence in chess history. He gave away both rooks, a bishop, and ultimately his queen, delivering checkmate with just three minor pieces. His opponent, Lionel Kieseritzky, was so astonished that he telegraphed the moves to Paris immediately.
The lesson it teaches: piece activity matters more than material. A pawn or a rook is only valuable if it is doing something. Anderssen's remaining pieces were so perfectly coordinated and active that three of them could finish off a full enemy army. When your pieces work together, they become more than the sum of their parts.