In reading of such sieges as these, one of the first things which strikes a reader not familiar with ancient warfare, is the extreme rudeness of the methods employed, and the vast expense of time and labour; yet, compared with earlier times, even the siege of Platæa is of no extraordinary duration. Not to go back to the ten–year sieges of Troy and Eira, the Messenians in Ithome held out against the Spartans during nine years; and, in the Peloponnesian war itself, Potidæa resisted for a still longer period than Platæa: such was the patience of a besieging army in waiting for the slow operation of hunger, or for some fortunate chance which, as at Eira, might give possession of the town at an unguarded moment. Before the battering–ram was invented, force could avail little against solid walls; and men soon found out, with Wamba, in Ivanhoe, that their hands were little fitted to make mammocks of stone and mortar. A well–conducted escalade might succeed; a skilful stratagem might deceive the vigilance of the garrison; an ingenious general might devise some method of attack which should render walls useless, as in the attempt to burn out the Platæans, and might derive some advantage from natural facilities, or even from natural obstacles, so as to convert what the besieged most trusted in into the means of their destruction; but to overthrow or pass the walls by violence was commonly beyond his power. But the introduction of the ram worked a material change in the relative strength of the besiegers and besieged, for few walls could be found strong enough to bear the repeated application of its powerful shocks. Next in importance to the ram were those huge moving towers which overtopped walls, and were provided with drawbridges, by means of which, the battlements being previously cleared of their defenders by missile weapons from above, a body of troops might at once be thrown upon them. [Illustration: Moveable towers, from Pompeii, vol. i. p. 80.] No material alteration in the methods of attack took place till the discovery of gunpowder gave force enough to projectiles to batter down the strongest walls, without exposing men and machinery to the hazard of close approach. The only improvements which did take place consisted in supplying means by which the assailants might approach with less danger to the foot of the walls, and there apply the powerful ram, or, in some instances, resort to mining.