Maastricht saw its population grow rapidly through immagration. Outside the gates, ribbon develpment took place, and new town quaters sprang up, for instance the cloth weavers' district before the Leugenpoort on the market square and the district in which the tanners and cloth dressers dwelt, between the branches of the Jeker stream in the south. Here, too, were the corn and oil mills, indispensable for the town's food supply. When it appeared that the ennemy coulkd stop the water mills on the Jeker by damming up the stream, the Maastricht population cane make use also of boat-mounted mills, the wheels of which were turned by the Maas water. Already in the 13th century the extension of the built-up area necessitatted the construction of a second, wider enceinte. This too was built in phases, starting with a moat and an eathwork, which were completed around 1300. In the course of the 14th century a stone wall was erected on top of the earthwork; it may be that the gateways were not reinforced in masonry until then. Constructtion started presumably around 1350. and the wall could be taken into use as a defence thirty years later; however, work on it continued, with the interruptions, for at least a century more. It was an enormous undertaking for a town that, probably, had fewer than 10.000 inhabitants. But the strained relations with the towns in the Liege country gave a continuing incentive to carry the fortifications of the town to a succesful conclusion. As Maasricht traditional supported the bishop against his subjects, the town in 1407 and 1408 had to undergo two sieges by the Lieges troops, and it was repeatedly threatened during civil wars that harassed the prince-bishopricbetween 1465 and 1492. The loyalty to its two sovereigns, the prince-bishop of Liege and the duke of Brabant- from 1430 the powerful dukes of Burgundy, and in the 16th century the emperor Charles V and king Philip II- made Maastricht a bulwark for the Burgundian-Habsburg expansion in the Netherlands.