The Opera Mate is a checkmate pattern that was demonstrated by Paul Morphy while watching Opera with the Duke of Brunswick and Count Isouard, in Paris, 1858.
Opera Mate Example
Diagram above: In this position Paul Morphy played 1.Qb8+! The only way black can escape the check is to accept the queen sacrifice, but it leads to checkmate on the next move.
Diagram above: Black had to capture white’s queen with 1… Nxb8, but now 2.Rd8# concludes the Opera Mate.
This checkmate idea is very similar to Mayet’s Mate. An important distinction is that in the case of the Opera Mate, the bishop also covers the square in front of the enemy king, whereas in the case of Mayet’s Mate, it doesn’t because the bishop defends the rook from the other side.
Why Is It Called the Opera Checkmate?
Paul Morphy played this game whilst watching an opera show. This Wikipedia entry shares quite a lot of detail on how it all happened and why it’s called the Opera Mate.