The Roman Empire began as a small city-state in the 7th century BC but had expanded greatly by the 1st century BC when it controlled much of what was Alexander the Great's former empire. Rome was a republic unlike the Greek city-states, with power concentrated in patricians, consuls, and proconsuls commanding legions. Julius Caesar seized control of the Roman senate in the 1st century BC after conquering Gaul from 58-51 BC. Though assassinated in 44 BC, his death did not restore the republic as hoped but instead led to civil war that nearly destroyed the empire.