農業革命
Karl Marx worried that the capitalist system would eventually lead to wages only sufficient for subsistence due to the tendency of the rate of profit to fall. Subsistence wages were indeed the case in parts of England. The British Agricultural Revolution had been reducing the need for labour on farms for over a century and these workers were forced to sell their labour wherever they could. Conditions were particularly bad during the depression years of the late 1830s to early 1840s. The depression was immediately followed by the Irish famine of 1845–50 which brought large numbers of Irish immigrants to seek work in the English and American factories.