While in the Southern provinces the Empire was thus dying from exhaustion, and the little isolated municipal states of the towns remained the only representatives of civil government left in the land, in Northern Gaul the invasions of the barbarians were much more frequent and numerous, so that almost every trace of Roman civilization was obliterated. But in the midst of all this decay and destruction of general government a new organising and centralising power was arising, in the form of the Christian Church. After passing through the fiery trials of the first three centuries Christianity had been adopted by Constantine in A.D. 313; and by the end of the fourth century the church had become an extensive and united institution, with a well organised hierarchy of clergy, revenues of its own, and provincial, national, and general councils. The vigour of the administration of the church system was conspicuous in the general laxity, and the control of affairs naturally fell into the hands of the ecclesiastical authorities—the priests and bishops. Their jurisdiction was officially recognised, and under the codes of Theodosius and Justinian the control of municipal affairs was remitted to the clergy and bishops, who were thus for a time in their respective cities the representatives of government and order.

From the date of Constantine till the overthrow of society, Barbarism, Paganism, and Christianity went on side by side. While civilisation remained the schools continued, Christians of antique learning and Pagan students discussed together the same problems of philosophy, and the Fathers endeavoured to reconcile them with Christianity. But as successive waves of Barbarians rushed over the land, drowning all before them, almost every semblance of learning was swept away. Hence arose a desire on the part of learned men to retire from the anarchy and insecurity of the conditions around them to some safe retreat, where they might converse on and study in peace those high problems which occupied their minds. These societies, in the natural course of events, were by degrees converted into monasteries. The celebrity of the Eastern ascetics and devotees had penetrated to Western Europe, but the solitary form of religious observance did not at first meet with much encouragement there. Societies of recluses were then, however, also common in the East, and the Eastern monastery was the form adopted by the Western recluses as their model. But monasteries were not at this time religious societies, nor were the monks in Holy orders. They were simply associations of laymen who wished to retire from the confusion and turmoil into which all civil government was thrown, and find peace for study and quiet for contemplation. Such was the famous monastery of the Lérins, founded early in the fifth century by St Honorat, on an island off the coast near Cannes, which soon became the most celebrated school of learning and piety in Southern Gaul, and was as great a blessing to the countries of the Mediterranean as the similar colony of St Columba at Iona was to the North of Britain.

It is easy, however, to fancy how, in the midst of the strife and unrest of the fifth and sixth centuries, such societies tended to become religious, and thus obtain protection from the Church. This they were finally compelled to do, although at the sacrifice of their liberty, by placing themselves under the authority of the bishops, where alone they could find rest and safety. For the Barbarians, many of whom were already Christians, stood in awe of the Church, and the Church strove to secure her ascendancy by maintaining the independence of the spiritual power, and the incapacity of the temporal powers to interfere with it; a doctrine which afterwards led to the terrible struggle for supremacy between the temporal and spiritual powers, represented on the one hand by the Emperor, and on the other by the Pope, a struggle which lasted so long, and involved so many cities in the horrors of the factions of the Guelphs and Ghibellines.

During the fearful reign of anarchy and destruction which prevailed in the sixth and seventh centuries, when all security for life and property had disappeared, and the armed hand of the Barbarian bore down all rule and order before it, the authority of the Bishops likewise gave way. Their Sees were invaded by Goths and Franks, who assumed their titles and drew their revenues. The fate of the monasteries was similar. The invaders seized the seats of the abbots, and the recluses were dispersed. Everywhere nothing but decay and disintegration prevailed. No wonder then, that monuments of this period are rare; the marvel is that any human structures should have survived the shock of universal ruin and destruction. Only a few of the more massive Roman monuments, built as if to last for ever, were able to withstand the tornado. The small and modest Christian edifices have been almost entirely swept away; but fortunately a few rare vestiges have been preserved within our district, sufficient to indicate the nature of the early Christian Architecture under the Empire.

By the eighth century the Barbarian invaders of Gaul had become somewhat settled in their new possessions, and had abandoned their original wandering mode of life. A certain nominal supremacy had always been accorded to the Merovingian Kings of the Franks, but the royal power, together with the title, had now passed into the stronger and more active hands of the Carlovingians, under whom it grew into a distinct royal authority.

At this time a new danger from an unexpected quarter threatened the slowly reviving prospects of the West, and seems for the moment to have had the effect of uniting all the otherwise discordant elements for the purpose of resistance to the common foe. This was the invasion of the Saracens from the South. These warlike zealots had, after over-running and destroying the Roman civilisation of Northern Africa, passed over into Spain, and in 719 they crossed the Pyrenees and invaded Southern Gaul. The old Roman cities were at that time in a comparatively settled and prosperous condition, when their tranquility was thus rudely interrupted. The whole country was devastated by the Saracen invaders, the towns were besieged, and in most cases taken and destroyed. We shall find, as we proceed, that there is scarcely one which does not bear the mark of the destructive hand of the Saracen. The overwhelming flood was, however, at length stemmed by Charles Martel in 732 at Tours, when the Moors were completely defeated and driven back beyond the Pyrenees. This great victory gave repose for a time; and thinking men being weary of the long night of Anarchy which had so long oppressed them, began to look round for some principle by which rule and order might again be restored. Any durable and fixed system would be better than the fluctuation and uncertainty so long experienced. After so many changes and so much diversity of government, the principle of unity naturally presented itself to men’s minds. The tyranny of the Empire was forgotten under the more crushing oppressions of all kinds which had since had to be submitted to; while its unity and strength were remembered, and people began to long for what now appeared to be “the good old times” of the Empire. It was agreed that the only satisfactory form of government was one which, like the Empire, should include the whole Roman world. This was considered to be in accordance with the nature of things. As there is one God, so there should be one Emperor to represent Him on earth as temporal ruler, and one Pope to represent Him in matters spiritual as the head of the Church. And by a remarkable coincidence this idea came to be realised about A.D. 800, in the person of Charlemagne, who extended his sway over nearly the whole of Western Europe. What rendered possible at that time the apparent fulfilment of the dream of universal temporal and spiritual government, was the fact that during Charlemagne’s time these two powers recognised that they could be of considerable service to one another, and were consequently on very friendly terms. As Charlemagne was now the supreme temporal Emperor, so the Bishop of Rome had also fully established his supremacy in the Church. This had been brought about by various fortunate circumstances—by his occupying the See of the great city whose name was still a power, and where the Bishop held the old municipal authority and rule which had there been less disturbed by the invasions of the Barbarians than elsewhere; by his importance as a suzerain, being a very extensive proprietor in Italy and Gaul; and by means of the influence of missionaries sent direct from Rome by the Pope to Britain and Germany, where the converts, being thus brought into immediate connection with Rome, naturally gave their support to the Pope as head of the Church.

The Papal sanction had now become usual, and was considered necessary by Kings, to their establishment on the throne—especially in Germany, where Papal supremacy so fully reigned. But while the King required the Pope’s countenance, the Pope also was most desirous to obtain the aid of the temporal power, in order to overthrow the authority of the Lombards in the North of Italy, and to obtain possession of the Exarchate.

Their requirements thus fitted in with one another, so that at the coronation of Charlemagne as Emperor by Pope Leo, in the year 800, the supremacy and unity of the two heads of affairs, in matters spiritual and temporal, seemed to be complete, and the Holy Roman Empire to be established on a secure and permanent basis.

After the time of Charlemagne, however, great disruptions of his empire ensued; but the idea of a central power took root, and although not developed according to the original conception, it led in time to the formation of the various nations which now occupy the different countries of Western Europe.

The idea of an universal Holy Empire deserves special attention in connection with Architecture. The same causes as led to this conception would also prevail with regard to the art, and especially the style of Architecture to be followed in the Empire. This we shall find there is reason to believe was the case, and that up to this time, and even till the tenth century, the churches were apparently erected in one traditional style, more or less followed in the whole of the Western Empire; whereas after the above date the architecture diverges into various national varieties in the different countries into which Europe was then sub-divided.