The links below are all gathered from the database Literati, a collection of reliable reference sources, and a good place to start for understanding concepts that are new to you.
Aaron Copeland's "Fanfare for the Common Man" was composed as America joined the fight for WWII. The performance above is by the New York Philharmonic and is performed at the closing of the dedication for the 9/11 Memorial in NYC on May 15, 2014. "Fanfare for the Common Man" has been considered a most American piece. To understand why, take a moment to read The Kennedy Center's ArtsEdge blog piece on "The Story Behind the Song: Fanfare for the Common Man."
To hear Copeland conducting his own piece, you can listen to the London Symphony Orchestra, streamed from the Libraries streaming music resource, Naxos Music Library.