The group auditioned Pete Best on 12 August 1960. Four days after hiring Best, the group left for Hamburg, beginning a 48-night residency at Bruno Koschmider's Indra Club, but moved to the Kaiserkeller in October 1960, after the closure of the Indra. They later accepted an offer to play at the rival Top Ten Club, which broke their contract with Koschmider, who reported Harrison to the German authorities for being under-age, leading to Harrison's deportation on 21 November 1960. McCartney and Best were arrested for arson a week later, after setting fire to a condom which they had hung on a nail in their room. They were also deported. Lennon returned to Liverpool in mid-December while Sutcliffe stayed behind in Hamburg with his new German fiancée, Astrid Kirchherr. The reunited group played an engagement on 17 December 1960 at The Casbah Coffee Club, with Chas Newby substituting for Sutcliffe.
The Beatles returned to Hamburg in April 1961, performing at the Top Ten Club again. They were recruited by singer Tony Sheridan (who also had a residency at the club) to act as his backing band on a series of recordings for the German Polydor Records label, produced by famed bandleader Bert Kaempfert. Kaempfert signed the group to a Polydor contract at the first session on 22 June 1961, and on 31 October Polydor released the recording "My Bonnie (Mein Herz ist bei dir nur)"—lead vocals by Sheridan—which appeared on the German charts. A few copies were also pressed under the American Decca Records label. When the group returned to Liverpool, Sutcliffe stayed in Hamburg with Kirchherr, so McCartney, unwillingly, took over bass duties.