The intro to “Don't Tread on Me” on Metallica's The Black Album interpolates music from West Side Story.
The borrowed melody comes from “America,” a well-known number composed by Leonard Bernstein for the musical. Metallica uses the melodic idea in the song's opening before moving into its own heavy arrangement and patriotic imagery.
West Side Story premiered on Broadway in 1957 and was created by a team including Bernstein, lyricist Stephen Sondheim, and director-choreographer Jerome Robbins. Its music became widely recognizable through both stage and film versions.
The connection is easy to miss because the interpolation is brief and surrounded by distorted guitars and drums. It is also distinct from a conventional cover: “Don't Tread on Me” remains a Metallica composition, with the musical reference appearing in the introduction. The song's title also echoes the motto associated with the Gadsden flag.