XLIII. While Demetrius lay dangerously ill at Pella, he very nearly lost his kingdom, as Pyrrhus invaded the country and briskly overran it as far as Edessa. However, on his recovery, Demetrius easily drove Pyrrhus out of Macedonia, and then made terms with him, because he did not wish to be entangled in a border warfare, which would interfere with the realisation of his more important projects. He meditated a colossal enterprise indeed, nothing less than the recovery of the whole of his father's empire. His preparations were on a commensurate scale, for he had collected a force of ninety-eight thousand foot soldiers and nearly twelve thousand horse, while at Peiræus, Corinth, Chalkis, and the ports near Pella he was engaged in the construction of a fleet of five hundred ships. He himself personally superintended the works, visiting each dockyard and giving directions to the artificers; and all men were astounded not only at the number, but at the size of the vessels which were being built. Before his time no one had ever seen a ship of fifteen or sixteen banks of oars, although in later times Ptolemy Philopator built a ship of forty banks of oars, which measured two hundred and eighty cubits in length, and forty-eight cubits in height. This ship was navigated by four hundred sailors, four thousand rowers, and, besides all these, had room upon its decks for nearly three thousand soldiers. But this ship was merely for show, and differed little from a fixed building, being totally useless, and only moved with great risk and labour; whereas the beauty of the ships of Demetrius did not render them less serviceable, nor was their equipment so elaborate as to interfere with their use, but they were no less admirable for speed and strength as for greatness of size.