They were abruptly stopped by the news of the massacre of St. Bartholomew, Orange's French allies being obliged to leave his army. [_PROTESTANT SUCCESSES_] Holland and Zeeland became henceforth the centre of resistance. These provinces had not taken an important share in the life of the Low Countries during the Middle Ages. Their prosperity was of comparatively recent date and mainly due to their merchant fleet, which brought to Antwerp wood and corn from the Baltic and wine from Bordeaux. Their sailors had ventured as far as Madeira and the Azores, and, on being stopped by Charles V from reaching America by the Southern route, had endeavoured to find a route to India by the North. From the beginning of the sixteenth century, Amsterdam had become the great corn market, Middleburg the centre of the French wine trade, and the shipyards of Vere, Goes and Arnemuyden were among the most active in Northern Europe. The influx of capital resulting from trade and shipping was used to reclaim marshes, to build fresh dikes and to increase considerably the cultivated area. Nowhere else, according to Guicciardini, was prosperity so general or did the traveller meet such "clean and agreeable houses and such smiling and well cared for country." Economically speaking, the Northern provinces were only beginning to feel the benefit of the advantages of their position, already so manifest in Antwerp. They were, so to speak, in a stage of formation, and far more ready to cut loose the links of tradition with an obscure past and to throw themselves into some great adventure in which they might try their strength. They occupied, besides, a safer situation than the South, controlling the outlets of three great streams and the adjoining seas, among low-lying lands which, as a last resort, could be flooded in order to stop the advance of an enemy or cut off his retreat. This situation adapted itself remarkably well to a defensive strategy by land and an aggressive strategy by sea. The small number of inhabitants and the small forces available rendered any offensive by land against the Spanish armies extremely dangerous, so that the Southern provinces, exposed on all sides to invasion, were left to shift for themselves. It so happened that the Prince of Orange, the principal leader of the opposition, had, as governor of Holland and Zeeland, acquired a great popularity in the country, which was considerably increased by his conversion to Calvinism. He had been made "Stadhouder" of his provinces and had found great resources in the confiscation of ecclesiastical property.