In 807 they became emboldened by success, and for the first time marched inland; and after burning Inishmurray, they attacked Roscommon.

During the years 812 and 813 they made raids in Connaught and Munster, but not without encountering stout resistance from the native forces.

After this predatory and internecine warfare had continued for about thirty years, Turgesius, a Norwegian prince, established himself as sovereign of the Vikings, and made Armagh his head-quarters, A.D.830.

If the Irish chieftains had united their forces, and acted in concert, the result would have been the expulsion of the intruders; but, unhappily, this unity of purpose in matters political has never existed.

The Danes made and broke alliances with the provincial kings at their own convenience, while these princes gladly availed themselves of even temporary assistance from their cruel foes, while engaged in domestic wars, which should never have been undertaken.
Still the Northmen were more than once driven from the country by the bravery of the native commanders, and they often paid dearly for the cruel wrongs they inflicted on their hapless victims.