In the great sea-wars of the past, Ireland has always been regarded by the enemy as providing the base for a flank attack upon England. Had King Louis XIV. rightly used his opportunities, the army of King William would have been cut off from its base in England, and would have been destroyed by reinforcements arriving from France to assist King James II. There is no more concise presentment of the case than the account of it given by Admiral Mahan in "The Influence of Sea Power upon History, 1660-1783." "The Irish Sea, separating the British Islands, rather resembles an estuary than an actual division; but history has shown the danger from it to the United Kingdom. In the days of Louis XIV., when the French navy nearly equalled the combined English and Dutch, the gravest complications existed in Ireland, which passed almost wholly under the control of the natives and the French. Nevertheless, the Irish Sea was rather a danger to the English--a weak point in their communications--than an advantage to the French. The latter did not venture their ships-of-the-line in its narrow waters, and expeditions intending to land were directed upon the ocean ports in the south and west. At the supreme moment the great French fleet was sent upon the south coast of England, where it decisively defeated the allies, and at the same time twenty-five frigates were sent to St. George's Channel, against the English communications. In the midst of a hostile people the English army in Ireland was seriously imperilled, but was saved by the battle of the Boyne and the flight of James II. _This movement against the enemy's communications was strictly strategic, and would be just as dangerous to England now as in 1690_[67].... "There can be little doubt that an effective co-operation of the French fleet in the summer of 1689 would have broken down all opposition to James in Ireland, by isolating that country from England, with corresponding injury to William's power.... "The battle of the Boyne, which from its peculiar religious colouring has obtained a somewhat factitious celebrity, may be taken as the date at which the English crown was firmly fixed on William's head. Yet it would be more accurate to say that the success of William, and with it the success of Europe, against Louis XIV. in the war of the League of Augsburg, was due to the mistakes and failure of the French naval campaign in 1690; though in that campaign was won the most conspicuous single success the French have ever gained at sea over the English." Every great naval power has gone to school to Admiral Mahan; and this country can hardly expect again to profit by those mistakes in strategy which the gifted American writer has so lucidly exposed.