The United States has a great length of coast line (over 2 1,000 miles apart from the Great Lakes), a large and valuable tonnage of coastal shipping and a steadily increasing ocean-growing mer cantile marine, all of which must be safeguarded. Already the U.S. navy is the equal of the British one in battleships, while it is very greatly superior numerically, in destroyers and submarines.
It is not unnatural, and it is certainly not a matter which causes resentment or suspicion amongst well-informed British people, that the American nation should desire some expansion of their "sea-police types" as their sea-borne trade and American owned shipping increases.
France, Italy and Japan (q.v.) have their own problems which they solve in their own way so far as their financial limitations permit. The two former are, of course, most concerned with their interests in the Mediterranean and their communications with North Africa. To them a large battle fleet makes less appeal than numerous torpedo craft and submarines, but both nations adhere to the battleship as being the predominant surface warship, while both find it necessary to build new and powerful cruisers. Japan has a navy second only to those of the British Empire and the United States. Her maritime interests neces sarily relate mainly to far eastern waters; her own defence and her trade in the China Seas and the Pacific.
So we can picture these five principal guardians of the oceans with their fleets balancing rather than challenging each other; their sea power centring in their main fleets, each with its quota, of battleships, but radiating to the distant seas, where representa tive cruisers and lesser craft are wont to co-operate harmoniously, no matter what their nationality, in keeping the peace and render ing the seas safe for those who pass upon their lawful occasions. To the student of history the influence which sea power has wielded in shaping the destinies of nations makes fascinating study. He will be able to trace the part which it played in the early struggles between Rome and Carthage and between the ancient Greeks and Persians; in the Peloponnesian War; in the extension westward of Mohammedan conquest ; in the crusades and in the progress of the Italian Republics and of the Ottoman Empire; in the rise and fall of one-time great sea nations like Spain, Portugal and the Dutch. But most of all must he be
struck by the history of the birth and growth of the British Empire and the part which sea power has played in promoting them.
He will find an exponent of the subject in as early a writer as Thucydides. But doubtless he will consider the works of Captain Mahan, U.S.N., particularly The influence of sea power upon history, The influence of sea power on the French revolu tion and empire and Nelson: The embodiment of the sea power of Great Britain to be more profitable studies. If, however, he would read the story of the most titanic struggle for sea power there has ever been and if he would realise all that victory at sea meant in the World War, let him turn to more recent works such as The history of the war—naval operations, Winston Churchill's World Crisis, or Earl Jellicoe's Grand Fleet and The Crisis of the Naval War. (See also, WORLD WAR: Naval; SUBMARINE CAMPAIGN.) In analysing the source of sea power it will not do to regard it as emanating solely from a fighting navy nor being dependent in scope and magnitude on the number and size of warships which a nation may acquire. Another important factor is the position and number of suitably placed bases for fuelling and refitting, as these are essential if naval influence is not to be confined to home waters or dependent on neutral goodwill in war. (See DOCKYARDS AND NAVAL BASES.) But perhaps the most potent element from an economic point of view in all that goes to give a nation power on the seas, is its mercantile marine because this represents solid wealth in the commerce which is borne across the oceans day by day and year by year and in the value of the ships which carry it. Navies, bases and all the machinery which goes to make up the defence of a nation's sea interests exist for two main purposes: to deny the seas to those who would make use of them for aggression, and to safeguard the shipping which bears passengers and freight from shore to shore. Ultimately, therefore, sea power is manifested in the use to which a nation puts sea transport in furthering its business and developing its trade and in giving facilities to its nationals to travel.