During Caesar's civil war the Parthians made no move, but maintained relations with Pompey. After his defeat and death, a force under Pacorus came to the aid of the Pompeian general Caecilius Bassus, who was besieged at Apamea Valley by the Caesarian forces. With the civil war over, Julius Caesar elaborated plans for a campaign against Parthia, but his assassination averted the war. During the ensuing Liberators' civil war, the Parthians actively supported Brutus and Cassius, sending a contingent which fought with them at the Battle of Philippi in 42 BC.