Ride of the Valkyries
opening of Act III of Der Walkure, #2/4 in Der Ring des Niebelungen
by Richard Wagner
performed as part of the Ring Cycle in 1870
performed separately in 1877
A process that happens to hit songs is that they acquire "secondary meaning." Secondary meaning is a concept that is well developed in trademark law, where it describes when a piece of intellectual property becomes associated closely enough with a generic term to justify protection, even though the trademark itself is descriptive.
When a song achieves "hit status," it begins to be taken out its original context and placed into a new context that may become more significant to the Audience then the original context of the work.
The common example of this is the use of pop songs in commercials and films, where the right placement can secure a new Audience for a specific older song for decades- think of Stand by Me in the film, Stand By Me or, the usage of Ride of the Valkyries by Francis Ford Coppola in Apocalypse Now:
That Youtube video of Ride of the Valkyries in Apocalypse Now has 2.6 million views. Richard Wagner has 3.5 million plays on Last FM... period. Six of his fifteen most popular tracks are versions of Ride of the Valkyries
It's fair to say that even given Richard Wagner as a still relevant dude within the world of Opera- I've seen productions of his works advertised in San Diego and Barcelona within the last six months alone- it's also fair to say that the Audience for Opera is dwarfed by the Audience for Film, and that as I write this, it's likely that more people know about Ride of the Valkyries from that one movie then know about the movie from their love of Opera. (I'd put that particular number at zero.)
With Ride of the Valkyries, we're talking about a song that was embedded in popular culture right from the get-go- initially perplexed by requests to hear Ride of the Valkyries separate from the Ring Cycle itself, he resisted until he gave in and conducted a performance... in London- in 1877.