Mercantilism was the school of thought that held that a positive balance of trade was of primary importance for any nation and required a ban on the export of gold and silver. This theory led to high protective tariffs to maximize the use of domestic resources, colonial expansion and exclusivity of trade with those colonies. British attempts to follow the mercantilist ideas led to the four Anglo-Dutch navigation wars and the American colonials wars of 1776-1781 and 1812. Additionally in 1815, Britain adopted the high tariff, called the corn laws on all imported wheat at the suggestion of mercantalist advisors. Debate over the corn laws would be harsh and would dominate the political discussion and occupy all British governments until the corn laws were repealed in 1846.