Following his 1987 exit from the German power metal band Accept, vocalistUdo Dirkschneider formed U.D.O. with guitarists Peter Szigeti and Mathias Dieth, bassist Frank Rittel, and drummer Tomas Franke. The group's debut album, Animal House, was in fact written by Dirkschneider's former bandmates in Accept, and by the time of the 1988 follow-up Mean Machine,Szigeti, Rittel, and Franke had all been dismissed, replaced by guitarist Andy Susemihl, bassist Thomas Smuszynski, and drummer Stefan Schwarzmann. Susemihl himself was out of U.D.O. for 1990's Faceless World, replaced by guitarist Wolla Böhm; the same roster recorded 1991'sTime Bomb, although the band split in the wake of a subsequent tour, withDirkschneider rejoining Accept from 1992 to 1996. He re-formed U.D.O. withDieth, Schwarzmann, guitarist Stefan Kaufmann, and bassist Michael Voss to contribute a track to the Judas Priesttribute album Legends of Metal; only Schwarzmann and Kaufmann remained on board for 1997's full-length Solid, which featured new guitarist Jürgen Graf-Biardi and bassist Fitty Weinhold. No Limits followed a year later, and in 1999U.D.O. resurfaced with Holy.