For some 75 years, historians have argued about the role that slavery and colonialism played in industrialisation. The key work on this subject was published in 1944 by the historian Eric Williams, who, significantly, came from the Caribbean and obtained his doctorate at Oxford. His hotly disputed thesis that the slave trade and colonial goods mass-produced by slaves, such as sugar, coffee and tobacco, provided the capital for the new coal mines and textile factories, has found new appreciation in the course of more recent debates on post-colonialism. At least for the beginning of the Industrial Revolution in Britain, concrete connections have now been proven: British traders trafficked some 2.5 million people from Africa to the plantations of the Caribbean and North America in the 18th century - more than any other nation. Wealth created by this trade flowed into the expanding industrial areas of Britain. But the extent of these investments and whether they played a decisive role in building the capitalist factory economy, as Williams thought, has not yet been conclusively established.

Other colonial powers, such as France and Portugal, shipped millions of Africans across the Atlantic and Indian Oceans to the highly profitable sugar cane plantations of their colonies, but industrialisation did not begin in those countries until the mid-19th century or later. A direct link is therefore difficult to discern, although there too, the immense influx of capital from the slave economy in the 18th century boosted their economies. Two economic historians have published one of the few detailed studies of the Netherlands: According to them, business with colonial goods from America accounted for about 20% of total Dutch foreign trade around 1770.

Not only shipping and shipbuilding earned money from this trade, but also banks, insurance companies and industries throughout Europe that processed or resold the imported goods: tobacco factories and coffee houses boomed across Europe, confectioners from Switzerland became masters in processing cocoa and spices from overseas, and in Cologne the Carl Joest sugar refinery was one of the most important taxpayers in the 19th century.

Added to this were the goods exchanged for slaves on the coasts of Africa: When the "Diligent" set sail from the French port of Vannes in May 1731 bound for West Africa, it had linen from Hamburg, shells from the Maldives, weapons and tobacco pipes from Holland as well as "Indiennes" on board, among other things. These colourfully printed fabrics made of Indian cotton enjoyed great popularity among African elites - many of them were manufactured in the most landlocked European country: Switzerland. The risky but profitable triangular trade between Africa, the colonies and Europe can be seen as an early form of globalisation that involved large parts of Europe.

Industrialisation then contributed significantly to the next wave of colonialism later in the 19th century. Now, even in later industrialised nations like France or the Netherlands, there was a huge demand for raw materials for production and markets for the products. Great Britain, a leading industrial nation as well as a colonial power, provided the prime example: raw cotton was imported from the Indian colony, then the local market was flooded with machine-woven fabrics, ruining the centuries-old Indian textile industry. Instead of sugar and coffee as consumer goods, European entrepreneurs now imported huge quantities of cotton, largely from the rapidly expanding slave plantations in the southern states of the USA. In addition, ores and agricultural products came from the colonies to supply the new industrial cities. Towards the end of the century, demand diversified as the electrical engineering, chemical and mechanical engineering sectors expanded in the "Second Industrial Revolution": copper, for example, came from the Belgian Congo, crude oil from Dutch Java, rubber from French Indochina. Driving the imperialist sabre-rattling of the powerful industrial nations and the increasingly aggressive rivalry for colonies, were the raw material needs of the dominant industries.

Industrialisation also started to change views about the morality of colonialism and slavery. In 1807, England abolished the slave trade in the British Empire followed in 1833 by the abolition of slavery in the British Empire. Although not the first country to do this, Britain’s naval superiority strengthened its ability to be able to enforce the new legislation worldwide. In Britain, public pressure led predominantly by evangelicals, was influential in bringing about the abolition of the slave trade and slavery.

In addition to the moral objections to slavery, there also developed economic objections as capitalism started to demand a different image of the world of work, based on the ideas of self-responsibility and the market economy. This involved the concept of the "free worker" rather than a slave economy and free trade instead of customs monopolies and trade restrictions. Historian Eric Williams believed that British factory owners and merchant entrepreneurs joined forces with philanthropists to bring about the end of slavery and advocate for free trade at the same time. Scholars still argue about how accurately he described the complex historical processes in England, though he did succeed in identifying an important principle of the new era, namely that slavery had to be abolished in order to raise the status of industrial workers. Even if industrial workers were forced to work 12 hours a day, received miserable wages and lived in appalling conditions, they were not slaves, they were "free". This was the ideological legitimisation that industrialised mass society needed.