The Third Macedonian War (171–168 BC) was a war fought between Rome and King Perseus of Macedon. In 179 BC King Philip V of Macedon died and his talented and ambitious son, Perseus, took his throne. Perseus married Laodike, daughter of King Seleucus IV Keraunos of Asia, and increased the size of his army. He also made alliance treaties with Epirus and several tribes of Illyria and Thrace, as well as enemies of Thracian tribes allied to Rome, such as the Sapaei under Abrupolis. He renewed former connections with some southern Greek city-states (poleis). The king announced that he could carry out reforms in Greece and restore its previous strength and prosperity.
King Eumenes II of Pergamon, who hated Macedonia, accused Perseus of trying to violate laws of other states and conditions of peace between Macedonia and Rome. The Romans were afraid for the balance of power in Greece and declared a new war with Macedonia. Perseus won the first struggle: the Battle of Callicinus, where he faced the army of Publius Licinius Crassus. The king offered a peace treaty to the Romans, which was refused. The Romans had problems with discipline in their army, and Roman commanders could not find a way to successfully invade Macedonia.
There was a stalemate near Phalanna involving Perseus and Crassus. In 169 BC, consul Quintus Marcius Philippus crossed the Olympus Range and entered Macedonia. However, his army ran out of provisions and retired on a narrow strip of coast near Tempe. Perseus tried to win Eumenes of Pergamon and King Antiochus IV of the Seleucid Empire over to his side but failed. He did, however, succeed in buying the support of the Illyrian king Genthius in the autumn of 169 BC. Perseus was defeated by the legions of the Roman consul Lucius Aemilius Paullus at the Battle of Pydna in 168 BC. This defeat was largely due to the inflexibility of Macedonian phalanx tactics compared to the maniple-based tactics of the Roman legions.
In the aftermath of this battle, King Perseus surrendered and was taken to Rome along with members of his court and other prisoners from the leading families of Macedon, including the historian Polybius. In addition, around 300,000 Macedonian citizens were enslaved. A number of Macedonian cities and villages were destroyed and their land distributed to the Roman veterans and their Thracian allies. Macedonia itself was divided into four Roman client republics, each of which was required to pay duty to Rome at half the rate previously due to the Macedonian kings. Economic and political contacts between the four republics were restricted. The Third Macedonian war marked the effective end of Hellenistic Macedonia and the monarchy of the Antigonid dynasty, and further enhanced Roman domination of Ancient Greece. Rome later returned to symbolically destroy Corinth in 146 BC in their war with Achaea, in a manner reminiscent of their destruction of the defanged Carthage in the Third Punic War.