Nialle "Caille", so called because he drowned in the River Caillen was the 166th Milesian Monarch of Ireland from 831 to 844. He fought many battles with the Danes and the Norwegians, in most of which, although the Danes were worsted, yet the continual supplies pouring unto them made them formidable - so much so, that in this reign, they took and fortified Dublin and other strongholds along the coast.