The Roman Republic was established after a violent overthrowing of Rome's monarchy. the reason for removing the monarchy is because, it was no longer an effective method of government, and the monarch has been abusing his power. The last king of Rome, Lucius Tarquinius Superbus, was actually from Rome's neighbor - the Etruscans. When Superbus was removed from power, he sought the assistance of the Etruscans to help him regain his position in Rome. this resulted into a war between the Romans and the Etruscans. After several battles, the Romans won the war, and were able to conquer the Etruscans later. In lieu of the king, they elected two consuls, and the senate as their new form of government - which is what we now know as the Roman Republic.
Republicanism is when people have the right to hold popular sovereignty rather than be subjects of the king; basically an republic. Liberalism combines ideas for civil liberty, equality, with support for social justice and mixed economy.
