Complex sentence: By this time, McGuigan had already incorporated the McGuigan Harrison Athletic Club, with an adjoining saloon, at 56 Harrison Avenue, and his club began to prosper, hosting fights between regional and national boxers, as well as dances and other events.
Split into simpler sentences: By this time, McGuigan had already incorporated the McGuigan Harrison Athletic Club, with an adjoining saloon, at 56 Harrison Avenue. His club then soon began to prosper, hosting fights between regional and national boxers, as well as dances and other events.