This chapter deals with Ireland's place in the more generic context of the origins of migration from the British Isles. The first crescendo of mass international migration came in the mid-1840s and was disproportionately Irish. Population growth, famine and emigration in the Irish case are commonly regarded as tied together inextricably. The spread of the potato facilitated economic expansion which included 'a huge movement of population from east to west with new communities growing up in previously little populated areas'. The potato failure in 1846 produced catastrophic levels of mortality and then massive migration. The evacuation of rural Ireland eventually issued forth into a flood of emigrants across the Irish Sea and across the Atlantic. Whatever the ideological assumptions, the readjustment of agriculture in Ireland, especially in the decades of the Great Famine, was radical and ruthless.