Those who are acquainted with the practical philosophy which directed operations in this war will readily foresee the choice which was now made. The business of mystery ships, as of all anti-submarine craft, was to sink the enemy. All other considerations amounted to nothing when this supreme object was involved. The lives of officers and men, precious as they were under ordinary circumstances, were to be immediately sacrificed if such a sacrifice would give an opportunity of destroying the submarine. It was therefore Captain Campbell's duty to wait for the under-water boat to sail slowly around his ship and appear in clear view on the starboard side, leaving his brave men at the stern exposed to the fire, every minute raging more fiercely, and to the likelihood of a terrific explosion. That he was able to make this decision, relying confidently upon the spirit of his crew and their loyal devotion to their leader, again illustrates the iron discipline which was maintained on the mystery ships. The first explosion had destroyed the voice tube by means of which Captain Campbell communicated with this gun crew. He therefore had to make his decision without keeping his men informed of the progress of events--information very helpful to men under such a strain; but he well knew that these men would understand his action and cheerfully accept their rôle in the game. Yet the agony of their position tested their self-control to the utmost. The deck on which they lay every moment became hotter; the leather of their shoes began to smoke, but they refused to budge--for to flee to a safer place meant revealing themselves to the submarine and thereby betraying their secret. They took the boxes of cordite shells in their arms and held them up as high as possible above the smouldering deck in the hope of preventing an explosion which seemed inevitable. Never did Christian martyrs, stretched upon a gridiron, suffer with greater heroism. V