Antigonid dynasty
In 148 BC, as a praetor, he led Roman troops into victory over Andriscus twice. Andriscus was a self-proclaimed pretender to the Macedonian throne who claimed to be son of Perseus, last king of the Antigonid dynasty. Andriscus had risen against Rome intending to liberate Macedonia with an army recruited from Thrace. Under Metellus' authority Macedonia was reduced and made a Roman province. For that he was awarded the "agnomen" Macedonicus, and since then introduced the "Clypeus Macedoniccus" in his family's medals.