Many naval officers at that time shared the same view. They opposed the convoy not only on these grounds; its introduction would mean immediately cutting down the tonnage 15 or 20 per cent., because of the time which would be consumed in assembling the ships and awaiting escorts and in the slower average speed which they could make. Many ship owners and directors of steamship companies expressed the same opinions. They also objected to the convoy on the ground that it would cause considerable delay and hence would result in loss of earnings. Yet the attitude of the merchant marine had not entirely eliminated the convoy from consideration. At the time when I arrived the proposal was still being discussed; the rate at which the Germans were sinking merchantmen made this inevitable. And there seemed to be two schools among Allied naval men, one of which was opposed to the convoy, while the other insisted that it should be given a trial. The convoy had one irresistible attraction for the officer which seemed to counterbalance all the objections which were being urged against it. Its adoption would mean taking the offensive against the German submarines. The essential defect of the patrol system, as it was then conducted, was that it was primarily a defensive measure. Each destroyer cruised around in an assigned area, ready to assist vessels in distress, escort ships through her own "square" and, incidentally, to attack a submarine when the opportunity was presented. But the mere fact that a destroyer was patrolling a particular area meant only, as already explained, that the submarine had occasionally to sink out of sight until she had passed by. Consequently the submarine proceeded to operate whenever a destroyer was not in sight, and this was necessarily most of the time, for the submarine zone was such a big place and the Allied destroyer fleet was so pitifully small that it was impossible to cover it effectively. Under these conditions there were very few encounters between destroyers and submarines, at least in the waters south and west of Ireland, for the submarines took all precautions against getting close enough to be sighted by the destroyers.