The 1870–1914 globalization period had profound impacts on the international division of labour, with coal-endowed countries specializing in the production of energy-intensive manufacturing goods and others in the production of agricultural goods. This study analyses the environmental consequences of this specialization, by quantifying the flows of energy and hidden energy embodied in the bilateral trade between the UK, the industrial workshop of the world, and Denmark, a coal-poor country with an agricultural economy. We show that the transformations that occurred in Danish agriculture to meet the growing demand for breakfast foods in the UK required significant quantities of feed and coal. Denmark was a net importer of energy throughout the period and a net importer of hidden energy in 1870. However, by the end of this wave of globalization, Denmark had become a significant net exporter of hidden energy to the UK. This was due both to an increase in its land productivity and to the import of coal, grain and fertilizers from abroad.