Complex sentence: Upon returning to the Senate, Julius Caesar is murdered by his fellow senators, who fear his increasing power and popularity amongst the citizens of Rome; however they are not able to gain the support of Marc Antony, who is appalled at their treachery.
Split into simpler sentences: Upon returning to the Senate, Julius Caesar is murdered by his fellow senators, who fear his increasing power and popularity amongst the citizens of Rome. However they are not able to gain the support of Marc Antony, who is appalled at their treachery.