How did the Roman Republic replace the Roman monarchy in 509 BCE?

The transition from the Roman monarchy to the Roman Republic in 509 BCE is traditionally attributed to a popular uprising against the tyrannical king Lucius Tarquinius Superbus.12

Traditional Narrative

According to Roman tradition, the king’s cruelty and the rape of the noblewoman Lucretia by the king's son sparked a revolt led by Lucius Junius Brutus. This uprising resulted in the expulsion of the Tarquin family and the abolition of the monarchy. Brutus is credited with establishing the foundational institutions of the Republic and serving as one of the first consuls.341

Modern Historical Perspective

Many modern historians view this traditional account as a patriotic, potentially unhistorical narrative influenced by Greek political theory. A prevalent alternative theory suggests the monarchy ended due to military defeat and foreign intervention. In this view, the Etruscan king Lars Porsenna defeated the Romans and expelled Tarquinius Superbus. When Porsenna was forced to withdraw without establishing his own rule, the Romans chose to replace the kingship with two annually elected magistrates rather than restoring the exiled monarch.32