Complex sentence: In May 1882 "The Bartered Bride" was given its 100th performance, an unprecedented event in the history of Czech opera, and so popular that a repeat "100th performance" was staged.
Split into simpler sentences: In May 1882 "The Bartered Bride" was given its 100th performance, an unprecedented event in the history of Czech opera. It was so popular that a repeat "100th performance" was staged.