Larry Mullen Jr. of U2's songs, helping to evoke military imagery. During the recording of the album "Pop" in 1996, Mullen suffered from severe back problems. Recording was delayed due to surgery. When he left the hospital, he arrived back in the studio to find the rest of the band experimenting more than ever with electronic drum machines, something driven largely by guitarist The Edge's interest in dance and hip-hop music, and, given his weakness after the operation, he relented, allowing The Edge to continue using drum machines, which contributed heavily to the album's electronic feel. Mullen has had tendinitis problems throughout his
War Tour kept in the set list. "40"'s show-closing, thoughtful presence – wherein The Edge and bassist Adam Clayton swapped instruments, then three band members left one by one leaving only drummer Larry Mullen, Jr. – grew into an audience participation ritual that would continue even after the band had left the stage. At one show at Dublin's Phoenix Park Racecourse, the fans' singing of the refrain "How long, to sing this song" from the song went on for 15 minutes after the concert's end. Initial British critical reaction to the first leg of the War Tour was favourable but with some