The war, which had started in 264 BC, continued after the Romans abandoned Africa, however, neither side gained a decisive advantage until 249 BC. The Romans rebuilt their fleet after losing 364 ships in a storm in 255 BC, added 220 new ships, captured Panormus (modern Palermo) in 254 BC, however, 150 ships were lost in another storm in 253 BC. The Romans had occupied most of Sicily by 249 BC and they besieged the last two Carthaginian strongholdsin the extreme west. The situation changed when the surprise attack on the Carthaginian fleet met defeat at the Battle of Drepana and the following Carthaginian victory at the Battle of Phintias; the Romans were all but swept from the sea. It was to be seven years before Rome again attempted to field a substantial fleet, while Carthage put most of its ships into reserve to save money and free up manpower.