On the huge chart already described the convoys, each indicated by a little boat, were shown steadily making their progress toward the appointed rendezvous. Eight or nine submarines, likewise indicated on the chart, were always waiting to intercept them. On that great board the prospective tragedies of the seas were thus unfolding before our eyes. Here, for example, was a New York convoy of twenty ships, steaming toward Liverpool, but steering straight toward the position of a submarine. The thing to do was perfectly plain. It was a simple matter to send the convoy a wireless message to take a course fifty miles to the south where, according to the chart, there were no hidden enemies. In a few hours the little paper boat, which represented this group of ships and which was apparently headed for destruction, would suddenly turn southward, pass around the entirely unconscious submarine, and then take an unobstructed course for its destination. The Admiralty convoy board knew so accurately the position of all the submarines that it could almost always route the convoys around them. It was an extremely interesting experience to watch the paper ships on this chart deftly turn out of the course of U-boats, sometimes when they seemed almost on the point of colliding with them. That we were able constantly to save the ships by sailing the convoys around the submarines brings out the interesting fact that, even had there been no destroyer escort, the convoy in itself would have formed a great protection to merchant shipping. There were times when we had no escorting vessels to send with certain convoys; and in such instances we simply routed the ships in masses, directed them on courses which we knew were free of submarines, and in this way brought them safely into port. III