This, however, was but an isolated effort, and though the Lombards held Classis, they achieved little else in Italy till after Authari was chosen king in 584. In the following year Smaragdus, as we may think, was appointed to succeed Longinus and apparently with new powers, and three years later, in the very year that the heroic Insula Comacina was taken by the Lombards, Classis was recovered for the empire. The Lombards had then been ravaging Italy for twenty years, an extraordinary change had come over the provinces that Justinian had so hardly recovered, and this change is at once visible in the imperial administration in Italy. The exarchate appears. It has been maintained by many historians that the great reform of which the establishment of the exarch and the exarchate is the result was the work of that very great reformer Justinian. It was worthy of him; but the Italy he knew and saved was not in need of any change in her administrative divisions which, as I have said, remained under Narses almost the same as they had been in the last days of the Western empire.[1] [Footnote 1: For what follows cf. Diehl, _Etudes sur l'administration Byzantine dans l'Exarchat de Ravenne_ (1888).] The transformation out of which the exarchate arose was slow and obscure, not the work of a great creative mind, but of necessity. It was the result of many causes which it is not difficult to name; they were the progress of the Lombard conquest, the condition imposed upon the unconquered parts of Italy by that conquest, and especially the new necessity for defence imposed on the imperial power. It is obvious that the result of the first ten years of that conquest was a complete destruction of the limits of the old Roman provinces of Italy. A new grouping of territories was not only necessary but was already forming itself under the pressure of the conquest and its terror. The regions which had escaped the barbarians were drawing together without any regard for the ancient provincial divisions and were grouping themselves about the cities, where the resistance, such as it was, was concentrating itself, and where the imperial administration had taken refuge. If we confine ourselves for the moment to Italy north of the Apennines, we shall find that in the old province of Liguria the vicar of the prefect of the praetorium had fled from Milan to Genoa, and that about that city the debris of the old province was slowly re-assembling itself. In Venetia we shall find that the governor had departed to Grado, and about this town as a centre the eastern part of the old province was gathered. The western part of that province, cut off from its capital, attached itself by force of circumstances to what remained of Aemilia and of Flaminia, whose neighbour she was, and these fragments of the ancient provinces all together grouped themselves about, or found their centre in, Ravenna, the capital of Flaminia and the residence of the prefect of Italy.