The first Umayyad caliph, Muawiyah I (r. 661–680), regarded the coastal towns of the Levant as strategically important. Thus, he strengthened Acre's fortifications and settled Persians from other parts of Muslim Syria to inhabit the city. From Acre, which became one of the region's most important dockyards along with Tyre, Mu'awiyah launched an attack against Byzantine-held Cyprus. The Byzantines assaulted the coastal cities in 669, prompting Mu'awiyah to assemble and send shipbuilders and carpenters to Acre. The city would continue to serve as the principal naval base of Jund al-Urdunn ("Military District of Jordan") until the reign of Caliph Hisham ibn Abd al-Malik (723–743), who moved the bulk of the shipyards north to Tyre. Nonetheless, Acre remained militarily significant through the early Abbasid period, with Caliph al-Mutawakkil issuing an order to make Acre into a major naval base in 861, equipping the city with battleships and combat troops.