(2) By far the most important cause of the American Revolution was the effort on the part of George III to enforce the navigation laws of Great Britain. It was customary then for every mother-country to regard its colonies as trading posts. The colonies were considered necessary as the source of raw materials for the home manufacturers and also as a market for the surplus manufactured goods of the home country. This economic principle was a phase of mercantilism which was the dominant economic doctrine of the time. In harmony with this theory, Great Britain as early as 1651 began passing navigation acts requiring her colonies to trade only with British merchants. All the export trade of the colonies had to be sent to Great Britain, and all their imported goods had to come from Great Britain. In addition, the ships transporting these goods had to be owned by British subjects. This law, however, was openly violated by the colonial merchants. They traded with the Dutch or with any other foreigners they could. British officials in America were bribed and co-operated in this illegal trade. The leading people of New England at this time were merchants, and it has been estimated that nine-tenths of these merchants were smugglers. John Hancock, who was to become president of the First Continental Congress in 1775, was a smuggler on a great scale, and at one time was sued for $500,000 as a penalty for smuggling. John Adams was his counsel. (See Simons, "Social Forces in United States History," pages 61-62.) It was these merchants of New England and especially of Boston, who were among the leaders in the Revolution. After the close of the French and Indian War in 1763, English merchants and English business in general had to be heavily taxed in order to pay the enormous national debt. Accordingly, pressure was brought to bear on the British government to have the navigation laws enforced, which would give the English the colonial trade, thus enabling them to meet more easily the financial demands of taxation. Efforts were then made by Great Britain to enforce these navigation laws which had been openly violated for more than a century. Their legality had never been questioned. It was the usual policy of all countries of that age in dealing with their colonies. These navigation laws were no doubt unwise interferences with trade but their legality was not questioned, as all modern tariffs are trade barriers, which does not make their violation legal. Besides, these laws did not entirely disregard the interests of the colonies. Great Britain gave them a monopoly of tobacco raising, prohibiting Ireland from raising it. Bounties or sums of money were often paid by the British Government to the colonial producers to encourage industry. These bounties were paid on indigo, tar, pitch, hemp, and many other industries which Great Britain was attempting to establish in the colonies in order to