Despite these successes, the Parthians were soon driven out of the Levant by a Roman counteroffensive. Publius Ventidius Bassus, an officer under Mark Antony, defeated and then executed Labienus at the Battle of the Cilician Gates (in modern Mersin Province, Turkey) in 39 BC. Shortly afterward, a Parthian force in Syria led by general Pharnapates was defeated by Ventidius at the Battle of Amanus Pass. As a result, Pacorus I temporarily withdrew from Syria. When he returned in the spring of 38 BC, he faced Ventidius at the Battle of Mount Gindarus, northeast of Antioch. Pacorus was killed during the battle, and his forces retreated across the Euphrates. His death spurred a succession crisis in which Orodes, deeply afflicted by the death of his favourite son, relinquished the throne to his other son Phraates IV ("r". c. 37–2 BC) as his new heir.