But about 1750 the conscience of New England awakened. Men in the pulpit took a strong position against the traffic. The Congregational churches of Vermont, Massachusetts, and Connecticut declared against slavery and asked the legislatures to adopt the Jewish law, emancipating all slaves whatsoever at the end of the tenth year of servitude. A little later, slavery was made illegal in all the New England colonies, Pennsylvania at length remembered William Penn, who had freed all his slaves in his will, while the German churches of that State began to expel all members who were known to have bought or held a slave. When, therefore, the convention met in Philadelphia, in 1776, preparatory to the Declaration of Independence, the delegates were able to say that as a whole the Northern colonies had cleansed their borders of the abuse, and had decided to build their institutions and civilization upon free labour, as the sure foundation of individual and social prosperity. But the antagonism to slavery in the Southern colonies was only less pronounced, and this, not because of economic reasons, but because of moral considerations. The Southern climate was friendly to cotton and tobacco, indigo and rice. These products made heavy demands upon labour, but white labour was unequal to the intense heat of the Southern summer and workmen were scarce. During the revolutions under King Charles I and Charles II and the wars at the beginning of the eighteenth century, England needed every man at home. Virginia offered high wages and large land rewards, but it was well-nigh impossible for her to secure immigrants and the labour she needed. In that hour the captain of a slave ship appeared in the House of Burgesses and offered to supply the need, but the people of Virginia instructed the delegates to the assembly to protest against the traffic. Finally, the colony imposed a duty upon each slave landing, and made the duty so high as to destroy the profits of the slave trade. King George was furious with anger, and sent out a royal proclamation forbidding all interference with the slave traffic under heavy penalty, and affirming that this trade was "highly beneficial to the colonies, as well as remunerative to the throne." Growing more antagonistic to slavery, the planters of Fairfax County called a convention at which Washington presided. Later, in Philadelphia, Benjamin Franklin brought in the resolutions condemning slavery as "a wicked, cruel and unjustifiable trade." Soon the leading men of the Southern colonies sent a formal protest to England. Lord Mansfield supported them in a decision that in English countries, governed by English laws, freedom was the rule, and slavery illegal, unless the colony, through its assembly, expressly legalized the slave traffic.