Having made some assaults which proved abortive owing to the strength of the place, Philip went away again, plundering the forts and villages in the country. Thence he marched to Prinassus and pitched his camp under its wall. Having promptly got ready his pent-houses and other siege artillery, he began to attempt the town by mines. This plan proving impracticable, owing to the rocky nature of the soil, he contrived the following stratagem. During the day he caused a noise to be made under ground, as though the mines were being worked at; while during the night he caused earth to be brought and piled up at the mouth of the mine, in order that the men in the city, by calculating the quantity of earth thrown up, might become alarmed. At first the Prinassians held out bravely: but when Philip sent them a message informing them that he had underpinned two plethra of their walls, and asking them whether they preferred to march out with their lives, or one and all to perish with their town when he set fire to the props, then at last, believing that what he said was true, they surrendered the city.