The political form of the Roman state for 400 years after the expulsion of Tarquin. The rule of a sole monarch yielded to the power of a landed aristocracy, the patricians, who ruled through two chief magistrates or consuls and an advisory body, the Roman Senate.

The city of Rome could operate as a ‘public concern’ as long as the small landed aristocracy managed the state. But, with overseas expansion, generals had to be given power to deal with problems abroad. Their substantial independence threatened republican tradition with its corporate government and brief periods of high office for individuals in rotation. Eventually the generals simply ignored the law, which required generals to lay down their commands on returning to Italian soil. The last of these commanders-in-chief, Octavian, achieved a settlement that appeared to combine republican institutions with personal military power. The Roman empire succeeded the republic.