When Henry came to the throne, he found the export trade mainly in the hands of two foreign groups--the Hansa, who had acquired privileges in England which they did not reciprocate, and the Venetians, who held their own without privileges by superior commercial acuteness--and of two English groups, the Merchants of the Staple, who controlled the wool markets, and the Merchant Adventurers, who were mainly interested in the manufactured goods. The King therefore followed a consistent policy of straining, in a restrictive sense, the interpretation of the concessions made to the Hansa, of emphasising grievances against them and of pressing for counter- privileges; and he successfully negotiated with Denmark in 1489 a commercial treaty, which interfered with the Hansa monopoly of the Scandinavian trade, by placing English merchants on a competitive footing with them. In a similar manner, he brought pressure to bear on the Venetians by opening direct relations with the Florentines at their port of Pisa. It is curious to note incidentally that the export dues on raw wool were enormously heavier than those on the manufactured goods; the difference being made in order to encourage the home sale of the wool and to stimulate the home manufacture by this means, as well as by encouraging the foreign sale of the manufactured goods. It is also observable that when an attempt was made by the London merchants to capture the worsted trade, Henry nipped it in the bud. It was no part of his policy to allow corporations--any more than individuals--to become powerful enough to demand terms for their political support. [Sidenote: The Navigation Acts] Recognising, as we saw, the commercial advantage to England of doing her own carrying trade and of multiplying ships and seamen, Henry--tentatively at first, but with increasing confidence--adopted artificial methods of encouraging this branch of industry, at the expense of free competition. Very early in the reign a Navigation Act required that goods shipped for England from certain foreign ports should be embarked on English vessels, during a specified period. Then the Act was renewed for a longer period, and finally without a time limit, and with more extended application. A great impetus was given to English shipping, with momentous results which can hardly have entered into Henry's calculations. He could not have anticipated the vast extensions of empire which were to be the prize of the nations with ocean-going navies, with the ocean itself for the great battlefield; or even the extent to which commerce and naval preponderance were destined to go hand in hand. The monopoly of the States with a Mediterranean sea-board was coming to an end. [Sidenote: Voyages of discovery]