The third mode of attack employed by the Assyrians in their sieges of fortified places was the mine. While the engines were in full play, and the troops drawn up around the place assailed the defenders of the walls with their slings and bows, warriors, singly, or in twos and threes, advanced stealthily to the foot of the ramparts, and either with their swords and the points of their spears, or with implements better suited for the purpose, such as crowbars and pickaxes, attacked the foundations of the walls, endeavoring to remove the stones one by one, and so to force an entrance. While thus employed, the assailant commonly either held his shield above him as a protection or was guarded by the shield of a comrade; or, finally, if he carried the curved _gerrhon_, leant it against the wall, and then placed himself under its shelter. [PLATE CX., Fig. 2.] Sometimes, however, he dispensed with the protection of a shield altogether, and, trusting his helmet and coat of mail, which covered him at all vital points, pursued his labor without paying any attention to the weapons aimed at him by the enemy. Occasionally the efforts of the besiegers were directed against the gates, which they endeavored to break open with axes, or to set on fire by an application of the torch. From this latter circumstance we may gather that the gates were ordinarily of wood, not, like those of Babylon and Veii, of brass. In the hot climate of Southern Asia wood becomes so dry by exposure to the sun that the most solid doors may readily be ignited and consumed. [Illustration: PLATE 111]