Sometimes the Danish chiefs mustered all their forces, and left the island for a brief period, to ravage the shores of England or Scotland; but they soon returned to inflict new barbarities on the unfortunate Irish.[199] Burning churches or destroying monasteries was a favourite pastime of these pirates, wherever they could obtain a landing on Christian shores; and the number of religious houses in Ireland afforded them abundant means of gratifying their barbarous inclinations.

But when they became so far masters as to have obtained some permanent settlement, this mode of proceeding was considered either more troublesome or less profitable than that of appropriating to themselves the abbeys and churches.
Turgesius, it is said, placed an abbot of his own in every monastery; and as he had already conferred ecclesiastical offices on himself and on his lady, we may presume he was not very particular in his selections.
The villages, too, were placed under the rule of a Danish captain; and each family was obliged to maintain a soldier of that nation, who made himself master of the house, using and wasting the food for lack of which the starving children of the lawful owner were often dying of hunger.
All education was strictly forbidden; books and manuscripts were burned and _drowned;_ and the poets, historians, and musicians imprisoned and driven to the woods and mountains.

Martial sports were interdicted, from the lowest to the highest rank.

Even nobles and princes were forbidden to wear their usual habiliments, the cast-off clothes of the Danes being considered sufficiently good for slaves.
The clergy, who had been driven from their monasteries, concealed themselves as best they could, continuing still their prayers and fasts, and the fervent recital of the Divine Office.

The Irish, true to their faith in every trial, were not slow to attribute their deliverance to the prayers of these holy men.
In 831 Nial Caille led an army against them, and defeated them at Derry; but in the meanwhile, Felim, King of Cashel, with contemptible selfishness, marched into Leinster to claim tribute, and plundered every one, except the Danes, who should have been alone considered as enemies at such a time.