Analysis of the political impact of naval force enters a new dirnension when this is applied to the causes and conduct of the Great War of 1914–18. In earlier wars navies had often been important in the actual fighting and the victories they won at sea sometimes had significant political consequences. The Portuguese Navy opened Asia to European dominance; the Dutch Navy made the political conquest of England possible; the French Navy became the midwife of American independence. The Great War, as the First World War was originally known, was fought and decided on land, the naval contribution being secondary in its importance and unexpected in its nature. Yet navies played a major part in causing that war, in prompting the participation as combatants of countries that might otherwise have remained neutral, and thus in determining the dimensions, duration and intensity of a war more destructive of European civilisation than any previous conflict. Few of these results had been intended, even imagined, by those who shaped naval policy before the war in any of the countries concerned.