During the 16th century, three major changes, economic, religious, and political, contributed to the further expansion of Dutch commerce. The first was the fragmentation of the Hanseatic League itself, of which the Dutch were major beneficiaries and agents, and which enabled them to establish a virtual monopoly of Scandinavian and Baltic trade. The second, and much more dramatic, event was the undermining of Antwerp’s commercial dominance by Spanish attempts to retain control of the Netherlands during the last third of the 16th century. The third was the declaration of independence from Spain made in 1581 by the seven northern provinces (Holland, Zeeland, Utrecht, Gelderland, Groningen, Friesland, Overijssel). Although the United Provinces did not secure final international recognition until the treaty of Westphalia in 1648, they were from the 1580s a formidable maritime force, opposed to Spanish hegemony on religious and political grounds. After Antwerp’s capture by Spanish forces in 1585, the United Provinces blocked the entry to the River Schelde and so cut the principal artery which linked Antwerp to Middelburg and the North Sea. The Dutch economy was thus for the first time decisively detached from the rest of the Netherlands in terms of capital, shipping, and the expertise of refugee Jews, who had earlier fled Spain and Portugal and migrated north with their commercial knowledge and connections to Amsterdam, which grew to become the major commercial, maritime, and banking centre of the western world for the next century or so. Amsterdam, in north Holland, became heir to the Hanseatic League’s Baltic trade and to Antwerp’s international banking and commerce.