In 1978 Peter Olsson started a band together with guitarist John "Jonta" Norum and drummer Bo "Werner" Sundberg. A couple of weeks later, "Werner" was replaced by Norum's friend Tony "Pippi" Niemistö, later known as Tony Reno. The band decided to adopt the name WC from Norum's previous band. In 1979 they were joined by vocalist Joakim "Jocke" Larsson, later known as Joey Tempest, and the band changed its name to FORCE..

Early in 1981 Peter left FORCE. The official explanation has been that he left because Joakim got together with his ex-girlfriend Anita Katila shortly after they broke up, however Peter told the complete story in the unauthorized EUROPE biography Only Young Twice in 2011: "It was I who broke up with Anita after we had been together for seven years. And I already had a new girlfriend when I found out that she had gotten together with 'Jocke', and for some reason I got jealous. And later on there was a drinking race where we started bitching and then I called it quits because I would never cope. The whole thing was my fault. I had no reason to be jealous. But I was also dissatisfied with FORCE's development. I wanted to play harder and more guitar based music and hadn't quite gotten the concept of choruses. For the most part I was after guitar masturbation, but I didn't understand that you have to prostitute yourself a bit to get anywhere.  It wasn't the kind of music I wanted to do and I don't think it was the kind of music 'Jonta' really wanted to do either. The way FORCE sounded in the beginning was just nonsense by today's standards. In a sense I regret leaving. But at the same time it would never have worked out between us in the long run. Furthermore I had a weak spot for beer already at that time, and I wouldn't have coped living the way that they would do. It would have crashed in every way. But at the same time I'm a bit proud of having been part of it and starting the band."

After Peter left FORCE, he joined Rising Force, the band of guitarist Yngwie J. Malmsteen. In 1983 he joined the band Power, who released a couple of singles, "Lying and Teasing" in 1986 and "Danger" in 1988, before splitting up in 1990.