Abu Ubaida and Khalid ibn Walid, after conquering all of northern Syria, moved north towards Anatolia taking the fort of Azaz to clear the flank and rear of Byzantine troops. On their way to Antioch, a Roman army blocked them near a river on which there was an iron bridge. Because of this, the following battle is known as the Battle of the Iron Bridge. The Muslim army defeated the Byzantines and Antioch surrendered on 30 October 637 CE. Later during the year, Abu Ubaida sent Khalid and Iyad ibn Ghanm at the head of two separate armies against the western part of Jazira, most of which was conquered without strong resistance, including parts of Anatolia, Edessa and the area up to the Ararat plain. Other columns were sent to Anatolia as far west as the Taurus Mountains, the important city of Marash, and Malatya, which were all conquered by Khalid in the autumn of 638 CE. During Uthman's reign, the Byzantines recaptured many forts in the region and on Uthman's orders, a series of campaigns were launched to regain control of them. In 647 Muawiyah, the governor of Syria, sent an expedition against Anatolia, invading Cappadocia and sacking Caesarea Mazaca. In 648 the Rashidun army raided Phrygia. A major offensive into Cilicia and Isauria in 650–651 forced the Byzantine Emperor Constans II to enter into negotiations with Muawiyah.