Original sentence: The Beatles residency in Hamburg, the German city where John Lennon, Paul McCartney, George Harrison, Stuart Sutcliffe  and Pete Best regularly performed at a series of four different clubs during the period August 1960 to December 1962, was a chapter in the group's history which honed their performance skills, widened their reputation, and led to their first recording, which brought them to the attention of Brian Epstein.The Beatles' booking agent, Allan Williams, decided to send the group to Hamburg when another group he managed, Derry and The Seniors, proved successful there
Edited sentence: The Beatles booking agent, Allan Williams, decided to send the group to Hamburg when another group he managed, Derry and The Seniors, proved successful there.The Beatles' residency in Hamburg, the German city where John Lennon, Paul McCartney, George Harrison, Stuart Sutcliffe  and Pete Best regularly performed at a series of four different clubs during the period August 1960 to December 1962, was a chapter in the group's history which honed their performance skills, widened their reputation, and led to their first recording, which brought them to the attention of Brian Epstein