Released in May 1967, "Sgt. Pepper's Lonely Hearts Club Band" is described by Doggett as "the biggest pop happening" to take place between the Beatles' debut on American television in February 1964 and Lennon's murder in December 1980. The album was a major critical and commercial success; through the level of attention it received from the rock press and more culturally elite publications, "Sgt. Pepper" achieved full cultural legitimisation for pop music and recognition for the medium as a genuine art form. Its win in the Album of the Year category at the 1968 Grammys Awards marked the first time that a rock LP had received this award. According to author Doyle Greene, the album provided "a crucial locus in the assemblage of popular music and avant-garde/experimental music – and popular culture and modernism". Chris Smith highlights "Sgt. Pepper" as one of the most "obvious" choices for inclusion in "101 Albums That Changed Popular Music", due to its continued commercial success, the wealth of imitative works it inspired, and its ongoing recognition as "a defining moment in the history of music".