Holland and Sweden reached their highest political importance about the same time, and here lies the explanation of their estrangement. The Dutch became jealous of the rising power of the North. In the beginning of the century the Dutch controlled the shipping of the Baltic, half of their enormous merchant fleet sailing on its waters and over two-thirds of the Swedish imports and exports for the period 1637–1643 were carried on foreign ships, the majority of which were Dutch. Swedish statesmen, however, endeavored to wrest this supremacy from the Hollanders, and through their efforts Swedish commerce and shipping increased greatly. Sweden soon became the leading power in the north. The States, fearing this supremacy, sided with her enemies and ruined many of her great plans. When Sweden stood almost ready to weld the three Scandinavian nations into one and make the Baltic a Swedish inland sea, Holland interfered, crushing her last hope of success. The Swedish colony on the Delaware passed over to the Dutch, and the Swedish possessions in Africa (1648–63) were captured by the same people. The Dutch now often seized Swedish merchant vessels, and for about half a century they did much damage to Swedish shipping and commerce. III. In this period Sweden developed a highly organized military system--in many respects the best in Europe--and the machinery of state was perfected to a degree not attained by any other European power at this early date. The government of the King lost most of its patriarchal features, and the division of labor became the watchword of the period. The military affairs of the nation were placed in the hands of the College of War, the management of the navy was assigned to the College of Admiralty (fully organized in 1634); the College of Mines (organized in 1637) superintended the mining industries; the re-organized financial system was given into the charge of the College of the Exchequer (_Kammarkollegium_, organized in 1618). “A general collector of customs”, aided by 110 assistants headed the customhouse service and an inspector superintended the surveying of the country (these two departments being branches of the _Kammarkollegium_).