Philidor's Legacy: A Guide to the Knight Sacrifice
From Good to Great: Pro-Level Tips
The Double-Check is the Setup
The classic smothered mate sequence begins with a knight check that is ALSO a discovered check from the queen (a double check). This is so forcing that the king MUST move. This forces the king into the corner, setting up the final sacrifice.
Clear the f7-Square
The entire combination hinges on your knight being able to land on the f7-square (or f2 for Black) to deliver the final blow. Your primary goal is to remove whatever piece is defending that square, no matter the cost.
A Move That Made History: Morphy vs. Duke of Brunswick, 1858 (The Opera Game)
While not a perfect smothered mate, the Opera Game is the spiritual ancestor of all such sacrifices. Morphy's stunning queen sacrifice, 15. Qd8+!!, serves the same purpose: to lure away a defender of a key square to allow his other pieces to flood in and deliver a swift mate. It embodies the sacrificial spirit required to find smothered mates.
The Winning Combination: 15. Qd8+!! Nxd8 16. Rad1# (A different mate, but the theme is similar)