Following the death of al-Walid I, Sulayman took up the project to capture Constantinople with increased vigor. In late 716, upon returning from the Hajj pilgrimage to Mecca, Sulayman encamped and mobilized his army in Dabiq in northern Syria. From there, he oversaw the massive war effort against the Byzantines. Being too ill to lead the campaign in person, he dispatched his half-brother Maslama ibn Abd al-Malik to besiege the Byzantine capital from the land, with orders to remain until the city was conquered or he was recalled by the Caliph. Already from early 716, the Arab commander Umar ibn Hubayra al-Fazari had launched a parallel naval campaign against Constantinople. While many troops were dispatched toward the Byzantine capital, Sulayman appointed his son Dawud to lead a summer campaign against the Byzantine frontier in 717, during which he captured Hisn al-Mar'a ("the Woman's Fortress") near Malatya.