Task: Question Answering
Input (English): Passage: Convinced now that the Greeks (and therefore the rest of the region) would not have peace if left alone, Rome decided to establish its first permanent foothold in the Greek world, and divided the Kingdom of Macedonia into four client republics. Yet, Macedonian agitation continued. The Fourth Macedonian War, 150 to 148 BC, was fought against a Macedonian pretender to the throne who was again destabilizing Greece by trying to re-establish the old kingdom. The Romans swiftly defeated the Macedonians at the Second battle of Pydna. Question: Who did Rome fight in the Fourth Macedonian War?
Output (English): a Macedonian pretender to the throne