In 67 BC Pompey was given the task of defeating Mithridates and Tigranes. Pompey first concentrated on attacking Mithridates while distracting Tigranes by engineering a Parthian attack on Gordyene. Phraates III, the Parthian king, was soon persuaded to take things a little further than an annexation of Gordyene when a son of Tigranes (also named Tigranes) went to join the Parthians and persuaded Phraates to invade Armenia in an attempt to replace the elder Tigranes with the Tigranes the Younger. Tigranes decided not to meet the invasion in the field but instead ensured that his capital, Artaxata, was well defended and withdrew to the hill country. Phraates soon realized that Artaxata would not fall without a protracted siege, the time for which he could not spare due to his fear of plots at home. Once Phraates left, Tigranes came back down from the hills and drove his son from Armenia. The son then fled to Pompey.