 Complete the following phrase:  His capture of the southern caverns of Cappadocia and the fortress of Ancyra in 739 marked the last Umayyad military gains in the wars with Byzantium. Despite the abortive attempts by his father Caliph Hisham ibn Abd al-Malik  to install Maslama as his chosen successor in place of al-Walid ibn Yazid, Maslama became a close companion of al-Walid and defended him from his fathers machinations. As a result, he was spared the fate of his brothers who were imprisoned upon al-Walids accession in 743. Nothing is heard of Maslama afterward and he may have been killed in a massacre of the Umayyad family by the Abbasids following their 