The siege of Motya took place either in 398 or 397 BC in western Sicily. Dionysius, after securing peace with Carthage in 405 BC, had steadily increased his military power and had tightened his grip on Syracuse. He had fortified Syracuse against sieges and had created a large army of mercenaries and a large fleet, in addition to employing the catapult and quinqueremes for the first time in history. In 398 BC, he attacked and sacked the Phoenician city of Motya despite the Carthaginian relief effort led by Himilco. Carthage also lost most of her territorial gains secured in 405 BC after Dionysius declared war on Carthage in 398 BC.