The first effects of a potato blight are reported around Ireland on September 9, 1845. An Gorta Mór, also known as the Great Famine or the Great Hunger, is a period of mass starvation, disease, and emigration in Ireland between 1845 and 1852. It is sometimes referred to, mostly outside Ireland, as the Irish Potato Famine, because about forty percent of the Irish population is solely reliant on this inexpensive crop for a number of historical reasons. During the famine, approximately 1 million people die and a million more emigrate from Ireland, causing the island’s population to fall by between 20% and 25%.
The proximate cause of famine is Phytophthora infestans, a potato disease commonly known as potato blight, which ravages potato crops throughout Europe during the 1840s. However, the impact in Ireland is disproportionate, as so much of the population is dependent on the potato for a range of ethnic, religious, political, social, and economic reasons, such as land acquisition, absentee landlords, and the Corn Laws, which all contribute to the disaster to varying degrees and remain the subject of intense historical debate.
The potato is introduced to Ireland as a garden crop of the gentry. By the late 17th century, it has become widespread as a supplementary rather than a principal food because the main diet still revolves around butter, milk, and grain products. However, in the first two decades of the 18th century, it becomes a base food of the poor, especially in winter. Furthermore, a disproportionate share of the potatoes grown in Ireland are of a single variety, the Irish Lumper. The expansion of the economy between 1760 and 1815 sees the potato make inroads into the diet of the people and become a staple food year round for farmers. The large dependency on this single crop, and the lack of genetic variability among the potato plants in Ireland, are two of the reasons why the emergence of Phytophthora infestans has such devastating effects in Ireland and less severe effects elsewhere in Europe.
It is not known exactly how many people die during the period of the famine, although it is believed that more die from diseases than from starvation. State registration of births, marriages, or deaths have not yet begun, and records kept by the Roman Catholic Church are incomplete. One possible estimate has been reached by comparing the expected population with the eventual numbers in the 1850s. A census taken in 1841 records a population of 8,175,124. A census immediately after the famine in 1851 counts 6,552,385, a drop of over 1.5 million in 10 years. The census commissioners estimate that at the normal rate of increase the population in 1851 should have been just over 9 million.
The famine is a watershed in the history of Ireland. Its effects permanently change the island’s demographic, political, and cultural landscape. For both the native Irish and those in the resulting diaspora, the famine enters folk memory and becomes a rallying point for various Irish Home Rule and United Ireland movements, as the whole island is then part of the United Kingdom of Great Britain and Ireland.
The massive famine sours the already strained relations between many of the Irish people and the British Crown, heightening Irish republicanism, which eventually leads to Irish independence in the next century.