THE WESTERN EMPIRE
IT was in the second decade of the ninth century, soon after the death of Charles the Great, that the first shock of viking aggression warned Louis the Pious of the danger from the north now menacing the calm and prosperous lands of the huge Frankish Empire. Just south of the mouth of the Loire on the big tidal island of Noirmoutier was the monastery of St. Philibert, not perhaps a provokingly wealthy institution, but one of some prosperity inasmuch as the island was a port of call for the barques employed in the salt-trade that was then, as now, the chief industry of the Breton marsh-lands. As such, Noirmoutier was doubtless well known to the northern adventurer-merchants, and it was this place that became the first goal of northern pirates in the Atlantic waters.
It may have been Norwegian vikings from Ireland, rather than Danes coming by the Channel route, who first of all plundered the abbey, but it was not long afterwards that the Danes found their way round Ouessant and sailed into the Bay of Biscay. Whether from Ireland or from Denmark, several times between the years 814 and 819 viking fleets appeared suddenly off the island and sacked the monastery, so that the abbot was compelled eventually to build temporary quarters for his monks inland on the Grand-lieu lake near Nantes, and here they were able to shelter during the months they soon learnt to recognize as the raid season. Later, Noirmoutier itself was fortified against the vikings, but the dangers of its island-position made defence against a viking fleet a peril worse than precipitate flight. Eventually the wretched and often ruined buildings of the monastery were abandoned, and the island became a viking-headquarters where the pirates could pass the winter; but this happened some twenty years after the early raids, and, as the opening of the viking attacks, it is sufficient to record the first plunderings of the abbey and also the sack about the same time of another monastery much further to the south on Ré island off Rochelle.
Louis may have paid little heed to these sudden and unex-