The intro to Metallica's song “Don't Tread on Me” interpolates music from which musical?

The intro to Metallica's song “Don't Tread on Me” interpolates music from the musical West Side Story. The borrowed melody was composed by Leonard Bernstein for that stage and film classic.

The reference appears at the beginning of the Black Album track, creating a brief contrast with the heavy guitar-driven arrangement that follows. The song's title and lyrics draw on the “Don't Tread on Me” motto associated with the Gadsden flag.

West Side Story was created with music by Leonard Bernstein, lyrics by Stephen Sondheim, and a book by Arthur Laurents. Its music includes the melody later associated with the “America” number, which is the source of the musical idea heard in Metallica's track.

The connection is easy to miss because Metallica uses the melody as a short introductory gesture rather than presenting a full quotation. It is one of the album's more distinctive background details and links a heavy-metal recording to a landmark American musical.