In Great Britain, industrial development led to the creation of new social groups and intensified long-standing conflicts between capital and labor. A new class of factory owners and industrial capitalists arose. These men and women and their families strengthened the wealth and size of the middle class, which had previously been made up mainly of merchants and professional people. The demands of modern industry regularly brought the interests of the middle-class industrialists into conflict with those of the people who worked for them — the working class. (See “Thinking Like a Historian: Making the Industrialized Worker.”) As observers took notice of these changes, they raised new questions about how industrialization affected social relationships. Meanwhile, enslaved labor in European colonies contributed to the industrialization process in multiple ways.