obstacles to a submarine blockade. But the situation of the British Isles is entirely different. They obtain from overseas the larger part of their food and a considerable part of their raw materials, and in April of 1917, according to reliable statements made at that time, England had enough food on hand for only six weeks or two months. The trade routes over which these supplies came made the submarine blockade a comparatively simple matter. Instead of the sticks of a fan, the comparison which I have suggested with our own coast, we now have to deal with the neck of a bottle. The trade routes to our Atlantic coast spread out, as they approach our ports; on the other hand, the trade routes to Great Britain converge almost to a point. The far-flung steamship lanes which bring Britain her food and raw materials from half a dozen continents focus in the Irish Sea and the English Channel. To cut the communications of Great Britain, therefore, the submarines do not have to patrol two or three thousand miles of sea-coast, as would be necessary in the case of the United States; they merely need to hover around the
extremely restricted waters west and south of Ireland.
This was precisely the area which the Germans had selected for their main field of activity. It was here that their so-called U-boats were operating with the most deadly effect; these waters constituted their happy hunting grounds, for here came the great cargo ships, with food and supplies from America, which were bound for Liverpool and the great Channel ports. The submarines that did destruction in this region were the type that have gained universal fame as the U-boats. There were other types, which I shall describe, but the U-boats were the main reliance of the German navy; they were fairly large vessels, of about 800 tons, and carried from eight to twelve torpedoes and enough fuel and supplies to keep the sea for three or four weeks. And here let me correct one universal misapprehension. These U-boats did not have bases off the Irish and Spanish coasts, as most people still believe. Such bases would have been of no particular use to them. The cruising period of a submarine did not depend, as is the prevailing impression, upon its supply of fuel oil and food, for almost any underwater boat was able to carry enough of these essential materials for a practically indefinite period; the average U-boat, moreover, could easily make the voyage across the
