Under Constans, the Byzantines completely withdrew from Egypt, and the Arabs launched numerous attacks on the islands of the Mediterranean Sea and Aegean Sea. Constans sent a fleet to attack the Arabs at Finike in 655, but was defeated; the Arabs were preparing to attack Constantinople when civil war broke out. In 658 he defeated the Slavs on the Danube River, temporarily slowing their advance throughout the Balkans.
He wanted to avoid the succession problems of his own reign, so he had his brother Theodosius murdered and named his sons Constantine, Heraclius, and Tiberius co-emperors. In 661 he campaigned against the Lombards in Italy, and decided to move the capital of the empire to Sicily; this was very unpopular, and he was assassinated in 668. Constantine succeeded him as Constantine IV.