Which Metallica song has an eight-bar introduction drawn from "America" in West Side Story?

Metallica's "Don't Tread on Me" has an eight-bar introduction drawn from "America," a song from the musical West Side Story.

The opening phrase is an interpolation rather than a conventional cover of the entire song. It uses a recognizable musical idea associated with Leonard Bernstein's score for West Side Story before moving into Metallica's own guitar-driven composition.

"Don't Tread on Me" appeared on Metallica's 1991 self-titled album and was later issued as a promotional single. Its title refers to the motto of the Gadsden flag, whose rattlesnake image also inspired the snake on The Black Album's cover. The lyrics use revolutionary and patriotic imagery, including references to liberty, peace, and preparedness.

James Hetfield and Lars Ulrich composed the music, while Hetfield wrote the lyrics. The song was not performed live until Metallica's 2012 European tour celebrating the album's twentieth anniversary, a detail that sometimes leads listeners to overlook it in discussions of the record.

The song is distinct from the album's five commercial singles. It received rock-radio promotion but did not have a standard commercial single release like "Enter Sandman" or "Nothing Else Matters."