The simple fact is that the battle fleet was never so safe as when it was cruising in the open sea, screened by destroyers. It was far safer when it was sailing thus defiantly, constantly inviting attack, than when it was anchored at its unprotected base at Scapa Flow. Indeed, until Scapa Flow was impregnably protected by booms and mines, the British commanders recognized that cruising in the open sea was its best means of avoiding the German U-boats. No claim is made that the submarine cannot dive under the destroyer screen and attack a battle fleet, and possibly torpedo one or more of its vessels. The illustration which has been given shows that Weddingen nearly "got" the _Neptune_; and had this torpedo gone a few feet nearer, his experiment might have shown that, although he subsequently lost his own life, crew, and ship, he had sunk one British battleship, a proceeding which, in war, might have been recognized as a fair exchange. But the point which I wish to emphasize is that the chances of success were so small that the Germans decided that it was not worth while to make the attempt. Afterward, when merchant vessels were formed into convoys, a submarine would occasionally dive under the screen and destroy a ship; but most such attacks were unsuccessful, and experience taught the Germans that a persistent effort of this kind would cause the destruction of so many submarines that their campaign would fail. So the U-boat commanders left the Grand Fleet alone, either because they lacked nerve or because their instructions from Berlin were explicit to that effect. II Having constantly before my eyes this picture of the Grand Fleet immune from torpedo attack, naturally the first question I asked, when discussing the situation with Admiral Jellicoe and others, was this: "Why not apply this same principle to merchant ships?" If destroyers could keep the submarines away from battleships, they could certainly keep them away from merchantmen. It is clear, from the description already given, precisely how the battleships had been made safe from submarines; they had proceeded, as usual, in a close formation, or "convoy," and their destroyer screen had proved effective. Thus logic apparently indicated that the convoy system was the "answer" to the submarine.