As soon as the disguised merchantman spotted this enemy she began to behave in character. When an armed merchant ship got within range of a submarine on the surface she frequently let fly a shot on the chance of a hit. That was therefore the proper thing for the _Dunraven_ to do; it was really all a part of the game of false pretence in which she was engaged. However, she took pains that the shell should not reach the submarine; this was her means of persuading the U-boat that it outranged the _Dunraven's_ gun and could safely give chase. The decoy merchantman apparently put on extra steam when the submarine started in her direction at top speed; here, again, however, the proper manoeuvre was not to run too fast, for her real mission was to get caught. On the other hand, had she slowed down perceptibly, that in itself would have aroused suspicion; her game, therefore, was to decrease speed gradually so that the U-boat would think that it was overtaking its enemy by its own exertions. All during this queer kind of a chase the submarine and the cargo ship were peppering each other with shells, one seriously, the other merely in pretence. The fact that a naval crew, with such a fine target as an exposed submarine, could shoot with a conscious effort not to hit, but merely to lure the enemy to a better position, in itself is an eloquent evidence of the perfect discipline which prevailed in the mystery ship service. Not to aim a fair shot upon the detested vessel, when there was a possibility of hitting it, was almost too much to ask of human nature. But it was essential to success with these vessels never to fire with the intention of hitting unless there was a practical certainty of sinking the submarine; all energies were focussed upon the supreme task of inducing the enemy to expose itself completely within three or four hundred yards of the disguised freighter.