Let's first start by defining mercantilism. In a nutshell, mercantilism depended on the belief that the amount of wealth in the world was static. This theory was developed in the early fifteenth century and was used as a point of reference by the European nations during the sixteenth through eighteenth centuries. Since the amount of wealth in the world was believed to be static, nations were working hard to collect as much of that wealth as possible.
Slavery was right at the center of mercantilism in Great Britain, as well as in other European nations. Great Britain created colonies all over the world, including in Africa and America. The main aim of these colonies was to control the available natural resources for the benefit of the British empire. Slaves were used as workers in British colonial farms where raw products such as sugar, cotton, and tea were produced. Mercantilist theorists believed that for a nation to be wealthy, it had to achieve a favorable balance of trade by importing less and exporting more. As a result, Great Britain used slaves to generate raw products in farms. These products were exported to throughout the empire, processed, and exported to other parts of the world as value-added products. This gave Great Britain an edge over its colonies, as well as other competing countries.