Which earlier musical work is interpolated in the intro to Metallica’s “Don’t Tread on Me”?

The intro to Metallica’s “Don’t Tread on Me” interpolates “America” from West Side Story.

“America” was composed by Leonard Bernstein for the musical West Side Story. Metallica used part of its melody in the introduction to “Don’t Tread on Me,” one of the songs on The Black Album. The reference is brief and appears before the band’s heavy arrangement takes over.

The connection is easy to miss because the album is usually discussed through its original riffs, production, and singles rather than its classical and musical-theater reference points. The interpolation is nevertheless documented in the album’s track notes and is a specific detail of the song’s construction.

“Don’t Tread on Me” is also notable for its title, which echoes the historical “Don’t Tread on Me” slogan associated with the Gadsden flag. That historical association is separate from the musical quotation. The melody in the intro comes from Bernstein’s “America,” not from a national anthem or a traditional patriotic march.