During the Second Punic War, Philip V of Macedon allied himself with Hannibal. Fearing possible reinforcement of Hannibal by Macedon, Rome dispatched forces across the Adriatic. Roman legions (aided by allies from the Aetolian League and Pergamon after 211 BC) did little more than skirmish with Macedonian forces and seize minor territory along the Adriatic coastline in order to "combat piracy". Rome's interest was not in conquest, but in keeping Macedon, the Greek city-states, and political leagues carefully divided and non-threatening. The war ended indecisively in 205 BC with the Treaty of Phoenice. While a minor conflict, it opened the way for Roman military intervention in Greece.
Macedonian Wars - Wikipedia, the free encyclopedia 