But to make conquests in Ireland, and to acquire by the sword alone permanent settlements there, were no easy tasks. The remote situation of Ireland, so far towards the west in the Atlantic Ocean, was of itself no slight defence. With the exception of certain tracts, principally on the east coast, the land is full of mountains, which everywhere afford secure retreats from an invading enemy. In our days Ireland, the second of the British Isles in point of magnitude, has a population of between six and seven millions, chiefly of ancient Irish, or Celtic origin; and in ancient times, when the Celts were entirely independent, and absolute masters of the country, the population does not appear to have been much less numerous. Ireland, moreover, distinguished itself by adopting Christianity, together with its accompanying civilization, at a very early period, which, however, was not able to put an end to the cruel and sanguinary disputes that raged between the different tribes composing its population. Thus the proportionately few and scattered Norwegians, who could reach Ireland only by sea, and who could derive assistance only from their countrymen settled upon the coasts of England and Scotland, had to contend with a numerous, and by no means unwarlike people, inhabiting an extensive and mountainous country. To obtain assistance in the hour of need from their own Scandinavian home was, on account of the great distance, a physical impossibility. When, therefore, we consider that neither the Romans nor the Anglo-Saxons ever obtained a footing in Ireland, although they had conquered the adjacent country, England; and when we further reflect upon the immense power exerted by the English in later times in order to subdue the Celtic population of Ireland, and the many centuries which elapsed before they even partially succeeded, we cannot help being surprised at the very considerable Scandinavian settlements which, as early as the ninth century, were formed in Ireland, and at the great influence which the Norwegians, according to the concurring evidence of the Irish and Scandinavian chronicles, must for more than three centuries have exercised in all the most important places in the country.