Complex sentence: During the convention, Chicago's Billy Goat Tavern gained notoriety for posting a notice saying "No Republicans Allowed," which caused the place to be packed with Republican conventioneers demanding to be served and led to increased publicity for the tavern.
Split into simpler sentences: During the convention, Chicago's Billy Goat Tavern gained notoriety for posting a notice saying "No Republicans Allowed". This caused Republican conventioneers to pack the place, demanding to be served, and led to increased publicity for the tavern.