The Romans invaded Greece during the Macedonian Wars. The Macendonians managed to hold out in the first two wars, although they had no victory in the second Macedonian war, they were only saved from destruction by surrendering some territory. Then the Romans probably decided that there was need for another war and in the third Macedonian war the Macedonians had to surrender all their territory.
See:
Romans
Macedonians
Macedonian wars