It was by giving stock that an Irish chief showed his power and added to his wealth. There were lands attached to his office, but his capital consisted of kine, and he extracted a sort of rent by obliging his inferiors to give them pasture. The number of cattle which he 'grazed without loss' upon other people's ground was the measure of his power and popularity. There were free tribesmen the amount of whose obligation to their chief was strictly laid down, though a greater quantity of stock might be voluntarily taken under certain restrictions. But there were also servile or semi-servile classes whose comparatively unprotected condition placed them more or less in the power of the chief to whose sept they were attached. An ambitious chief would always have opportunities of aggrandisement, and his wealth enabled him to support a mercenary force, and to grow strong at the expense of his own and other tribes. Broken men who had lost their own tribal position would always flock to an ambitious chief, and the disturbing influence of such retainers was often too strong for Brehons or priests. But the growth of power by means of mercenaries was not peculiar to Ireland, and was perhaps less frequent than is commonly supposed.[4] [Sidenote: Frequency of war.] Whatever the advantages of a pure Celtic system, it did not secure general peace. There is no period of which Celtic Ireland may be more justly proud than that between the death of St. Columba in 597 and the death of St. Gall about 640. It was the age in which the Irish saint Columbanus bearded Thierri and Brunehaut, in which Ireland herself was a noted seat of learning, and in which the monasteries of Luxueil, of St. Gall, and of Bobbio were founded by Irishmen. Yet, under thirty years out of forty-four either battle or murder is recorded in the _Chronicon Scotorum_. In some years there were several battles and several murders. In 628 Leinster was devastated. Quarrels between near relations were frequent, and often ended in murder. When we consider that the deaths of important people only are recorded, we cannot pronounce the Ireland which sent forth Aidan, and Adamnan, and Columbanus to have been at all a peaceful country. Christianity was then established, and no Scandinavian irruption had yet hindered the development of purely native ideas. But Irish chroniclers, perhaps owing to their genealogical turn, give a disproportionate space to deaths; and it may be admitted that the number of homicides was not greater in Ireland than in some parts of Germany in feudal times.[5] [Sidenote: Celtic law of succession.]