Williams specialised in the study of slavery. Many Western academics focus on his chapter on the abolition of the slave trade, but that is just a small part of his work. In 1944 his book "Capitalism and Slavery" argued that the British abolition of their Atlantic slave trade in 1807 was motivated primarily by economics—rather than by altruism or humanitarianism. By extension, so was the emancipation of the slaves and the fight against the trading in slaves by other nations. As industrial capitalism and wage labour began to expand, eliminating the competition from slavery became economically advantageous.