The area of the North Sea alone exceeds 140,000 square miles, and when the whole vast stretch of water encompassed by what was known as the radius of action of hostile submarines, from their bases on the German, Belgian, Austrian, Turkish and Bulgarian coasts, had to be considered as a possible zone of operations for German and Austrian under-water flotillas, much of the water surface of the world was included. Likewise the network of sea communications on which the Allies depended for the maintenance of essential transport and communication comprised the pathways of the seven seas. To patrol all these routes adequately, and to guard the food and troop ships, hastening in large numbers to the aid of the Motherland from the most distant corners of the earth; to protect the 1500 miles sea frontier of the British Isles; to give timely aid to sinking or hard-pressed units of the mercantile fleet; to hound the submarine from the under-seas and to sweep clear, almost weekly, several thousand square miles of sea, from Belle Isle to Cape Town and the Orkneys to Colombo, required ships, not in tens, but in thousands. To find these in an incredibly short space of time became the primary naval need of the moment. Who that lived through those days will forget the struggle to supply ships and guns? The searching of every harbour for craft, from motor boats to old-time sailing-ships, and from fishing craft to liners. The scouring of the Dominions and Colonies. How blessed was their aid! Help, generous and spontaneous, came from all quarters, including the most unexpected. Over five hundred fast patrol boats, or motor launches, in less than twelve months from Canada and America. Guns from Japan. Coasting steamers from India, Australia, New Zealand and South Africa. Seaplanes from the Crown Colonies. Rifles from Canada. Machine guns from the United States. Ambulances from English and Colonial women's leagues. In fact, contributions to the "new navy" from all corners of the earth. To patrol the coasts of Britain alone, and to keep its harbours and coastal trade routes clear of mines, needed over 3500 ships, with at least an equal number of guns, 30,000 rifles and revolvers, and millions of shells. In addition to this huge fleet other smaller squadrons were required for the Mediterranean, the Suez Canal and Red Sea, the East and West Indies, the coasts of the Dominions and Colonies, and for the Russian lines of communication in the White Sea. For these oversea bases just under 1000 ships were required, exclusive of those locally supplied by the Dominions and Colonies themselves.