In 1485 the rivalry between Antwerp and Bruges reached the point of open war. The men of Bruges built a fort commanding the River Scheldt at a point near Calloo, mounting on it no less than sixty cannon. The Antwerp burghers met this challenge by building a similar fort at Austruwel, and then attacked and captured the Flemish fort on April 23--St. George's Day. A yearly procession still commemorates this victory in the long contest to maintain the freedom of the river. A fleet of forty-nine merchant vessels that the Flemings had detained came triumphantly up the river, and the conflict for supremacy between the old sea gateway of the Netherlands and the new was settled once for all--as far as poor Bruges was concerned--in favour of Antwerp, the new maritime queen of the North. The river itself seemed to favour the prosperity of Antwerp, as if proud and eager to become the handmaiden of so valiant and beautiful a city, for the western entrance of the Scheldt gradually deepened at about this period--from causes that in those days no one tried to understand. This gave the port a deep channel to the sea to accommodate the growing draught of ocean-going ships. The discoveries of Columbus and Vasco da Gama helped the port also. Until then Venice had enjoyed a monopoly of the sugar trade of the East. Now it came sea-borne to Antwerp, and the formerly profitable overland sugar trade between Venice and Germany was ruined. This caused the Portuguese to establish a factory at Antwerp. The Spaniards followed, while the English and Italians enlarged their warehouses. Several great German trading houses opened premises in the city, although the Hanseatic League did not abandon Bruges for Antwerp until 1545--being the very last to go.