The Admiralty in London was thus the central nervous system of a complicated but perfectly working organism which reached the remotest corners of the world. Wherever there was a port, whether in South America, Australia, or in the most inaccessible parts of India or China, from which merchantmen sailed to any of the other countries which were involved in the war, representatives of the British navy and the British Government were stationed, all working harmoniously with shipping men in the effort to get their cargoes safely through the danger zones. These danger zones occupied a comparatively small area surrounding the belligerent countries, but the safeguarding of the ships was an elaborate process which began far back in the countries from which the commerce started. Until about July, 1917, the world's shipping for the most part had been unregulated; now for the first time it was arranged in hard and fast routes and despatched in accordance with schedules as fixed as those of a great railroad. The whole management of convoys, indeed, bore many resemblances to the method of handling freight cars on the American system of transcontinental lines. In the United States there are several great headquarters of freight, sometimes known as "gateways," places, that is, at which freight cars are assembled from a thousand places, and from which the great accumulations are routed to their destinations. Such places are Pittsburg, Buffalo, St. Louis, Chicago, Minneapolis, Denver, San Francisco--to mention only a few. Shipping destined for the belligerent nations was similarly assembled, in the years 1917 and 1918, at six or eight great ocean "gateways," and there formed into convoys for "through routing" to the British Isles, France, and the Mediterranean. Only a few of the ships that were exceptionally fast--speed in itself being a particularly efficacious protection against submarines--were permitted to ignore this routing system, and dash unprotected through the infested area. This was a somewhat dangerous procedure even for such ships, however, and they were escorted whenever destroyers were available. All other vessels, from whatever parts of the world they might come, were required to sail first for one of these great assembling points, or "gateways"; and at these places they were added to one of the constantly forming convoys. Thus all shipping which normally sailed to Europe around the Cape of Good Hope proceeded up the west coast of Africa until it reached the port of Dakar or Sierra Leone, where it joined the convoy. Shipping from the east coast of South America--ports like Rio de Janeiro, Bahia, Buenos Aires, and Montevideo--instead of sailing directly to Europe, joined the convoy at this same African town. Vessels which came to Britain and France by way of Suez and Mediterranean ports found their great stopping place at Gibraltar--a headquarters of traffic which, in the huge amount of freight which it "created," became almost the Pittsburg of this mammoth transportation system. The four "gateways" for North America and the west coast of South America were Sydney (Cape Breton), Halifax, New York, and Hampton Roads. The grain-laden merchantmen from the St. Lawrence valley rendezvoused at Sydney and Halifax. Vessels from Portland, Boston, New York, Philadelphia, and other Atlantic points found their assembling headquarters at New York, while ships from Baltimore, Norfolk, the Gulf of Mexico, and the west coast of South America proceeded to the great convoy centre which had been established at Hampton Roads.