 The Parthian threat to the Triumvirate's rule was urgent due to the fact that the Parthians supported the Liberators in the recent civil war, aid which included the supply troops at Philippi.As ruler of the East, Antony also assumed responsibility for overseeing Caesar's planned invasion of Parthia to avenge the defeat of Marcus Licinius Crassus at the Battle of Carrhae in 53 BC.In 42 BC, the Roman East was composed of several directly controlled provinces and client kingdoms.