The municipal government of Lombardy grew up gradually and almost imperceptibly under the shade of the episcopal power. The townsfolk became more numerous and more wealthy. The inland cities became great seats of manufacturing industry, important market centres, or, like Bologna and Padua, famous for their schools. The towns on or near the sea found even greater prosperity through foreign trade. The necessity of common action in business, no less than juxtaposition in common residence behind strong walls, brought together the citizens in a common unity of feeling. The very subordinate agents of the bishops’ power supply the rudiments of a common organisation. The eleventh century very commonly saw the citizens in revolt against their episcopal protectors. Milan, when on the side of its archbishop, had been strong enough to enable Aribert to wage war against the Emperor himself [see pages 58, 59]. In the next generation Milan and its archbishops were generally at war. The quarrel of Pope and Emperor made it easy for the dexterous townsmen to play the ecclesiastical and the temporal authority against each other, and Popes and Emperors alike were prepared to bid heavily for its support. Thus the ‘regalia,’ which the bishops had usurped from the counts, passed in some way from them to the citizens. By the beginning of the twelfth century the great towns of the north had become self-governing municipalities. At the head of the municipal organisation stood the _consuls_, the chief magistrates of the town, varying widely in numbers, authority, and method of appointment, but everywhere the recognised heads of the city state. The consulate, which began in Italy towards the end of the twelfth century, was in its origin a sworn union of the citizens of a town bent upon obtaining for themselves the benefits of local autonomy. Private, and often, like the North French _Commune_, rebellious in its early history, the consulate in the end obtained the control of the municipal authority. With its erection or recognition begins the independent municipal organisation of the Italian cities.[17] Besides the ruling consuls was a council, or _credentia_, of the ‘wise men’ of the city, acting as a senate. Beyond these governing bodies was the _communitas_, meeting on grave occasions in a common _parlamentum_ or conference. The local life of the municipalities was intensely active, but there were fierce jealousies and perpetual faction fights between the different orders of the population. The even more violent local hatred of neighbouring cities made common action almost impossible, and led to constant bloody wars. But despite these troubles, the Lombard cities grew in wealth, trade, numbers, and reputation. [Sidenote: The Tuscan cities.]