Even if it had not been recovered at the time, the British would have regained possession with their next advance; for the Germans had no way of taking a tank to the rear. There are no tractors powerful enough to draw one across the shell-craters. It can be moved only by its own power, and with its engine out of order it becomes a fixture on the landscape. Stranded tanks have an appearance of Brobdingnagian helplessness. They are fair targets for revenge by a concentration of German artillery fire; yet when half hidden in a gigantic shell-hole which they could not navigate they are a small target and, their tint melting into the earth, are hard to locate. Seen through the glasses, disregarding ordinary roads and traveled routes, the tanks' slatey backs seemed like prehistoric turtles whose natural habitat is shell-mauled earth. They were the last word in the business of modern war, symbolic of its satire and the old strife between projectile and armor, offensive and defensive. If two tanks were to meet in a duel, would they try to ram each other after ineffectually rapping each other with their machine guns? "I hope that it knows where it is going!" exclaimed a brigadier-general, as he watched one approach his dugout across an abandoned trench, leaning over a little as it dipped into the edge of a shell-crater some fifteen feet in diameter with its sureness of footing on a rainy day when a pedestrian slipped at every step. There was no indication of any guiding human intelligence, let alone human hand, directing it; and, so far as one could tell, it might have mistaken the general's underground quarters for a storage station where it could assuage its thirst for gasoline or a blacksmith's shop where it could have a bent steel claw straightened. When, finally, it stopped at his threshold, the general expressed his relief that it had not tried to come down the steps. A door like that of a battleship turret opened, and out of the cramped interior where space for crew and machinery is so nicely calculated came the skipper, who saluted and reported that his ship awaited orders for the next cruise.