On the other hand, the Irish never ceased from war with the sea-kings. From the time of Thorgils, high-kings of Tara one after another led the perpetual contest to hold Ireland and to possess Dublin. They summoned assemblies in north and south of the confederated chiefs. The Irish copied not only the Scandinavian building of war-ships, but their method of raising a navy by dividing the coast into districts, each of which had to equip and man ten ships, to assemble at the summons for the united war-fleet. Every province seems to have had its fleet. The Irish, in fact, learned their lesson so well that they were able to undertake the re-conquest of their country, and become leaders of Danish and Norse troops in war. The spirit of the people rose high. From 900 their victories increased even amid disaster. Strong kings arose among them, good organisers and good fighters, and for a hundred years one leader followed hard on another. In 916, Niall, king of Tara, celebrated once more the assembly of Telltown, and led southern and northern O'Neills to the aid of Munster against the Gentiles, directing the men of Leinster in the campaign--a gallant war. Murtagh, king of Ailech or Tirconnell, smote the Danes at Carlingford and Louth in 926, a year of great danger, and so came victorious to the assembly at Telltown. Again, in 933, he defeated the "foreigners" in the north, and they left two hundred and forty heads, and all their wealth of spoils. In 941 he won his famous name, "Murtagh of the Leather Cloaks," from the first midwinter campaign ever known in Ireland, "the hosting of the frost," when he led his army from Donegal, under shelter of leather cloaks, over lakes and rivers frozen by the mighty frost, round the entire circuit of Ireland. Some ten years later, Cellachan, king of Cashel, took up the fight; with his linen-coated soldiers against the mail-clad foreigners, he swept the whole of Munster, capturing Limerick, Cork, Cashel and Waterford, and joining their Danish armies to his own troops; till he closed his campaign by calling out the Munster fleet from Kinsale to Galway bay, six or seven score of them, to meet the Danish ships at Dundalk. The Norsemen used armour, and rough chains of blue iron to grapple the enemies' ships, but the Irish sailors, with their "strong enclosures of linen cloth," and tough ropes of hemp to fling over the enemies' prows, came off victorious. According to the saga of his triumph, Cellachan called the whole of Ireland to share in the struggle for Irish freedom, and a fleet from Ailech carried off plunder and booty from the Hebrides. He was followed by Brian Boru. "Ill luck was it for the Danes when Brian was born," says the old saga, "when he inflicted not evil on the foreigners in the day time he did it in the next night." From beyond the Shannon he led a fierce guerrilla war. Left with but fifteen followers alive, sleeping on "hard knotty wet roots," he still refused to yield. "It is not