During the early centuries of its existence, Constantinople faced few naval threats. Especially after the wars of Justinian, the Mediterranean had again become a "Roman lake". It was during the first siege of the city by the Avars and the Sasanid Persians that for the first time, a naval engagement was fought off the city itself. After the Arab conquests of Syria and Egypt, a new naval threat emerged. In response, the sea walls were renovated in the early 8th century under Tiberios III (r. 698–705) or Anastasios II (r. 713–715). Michael II (r. 820–829) initiated a wide-scale reconstruction, eventually completed by his successor Theophilos (r. 829–842), which increased their height. As these repairs coincided with the capture of Crete by the Saracens, no expense was spared: As Constantine Manasses wrote, "the gold coins of the realm were spent as freely as worthless pebbles". Theophilos' extensive work, essentially rebuilding the sea walls, is testified to by the numerous inscriptions found or otherwise recorded that bear his name, more than those of any other emperor. Despite future changes and restorations, these walls would essentially protect the city until the end of the empire.