Alexander : a history of the origin and growth of the art of war from ...

172 SCALING WALLS.Thebes, and Campaneus, one of the kings and their inventor,is said to have lost his life in falling from one of his own ladders.A later means was the tortoise, made, as has been alreadydescribed, by joining together buclders, or shields, abovethe heads of a massed force, on which a second party conldScaling- Ladders.stand to scale the walls or form a second tortoise for thescalers. But these crude methods soon gave way to moreregular means, which aimed at making a defense againstsorties from within and against relieffrom without, at erectinga shelter from the enemy's fire and at organizing vigorousmeasures of attack.A wall of contravallation to inclose the town or fortress andkeep the garrison within its defenses was first built ; then out-