A very controversial and pivotal event in Irish and British history. The root (teehee) of the famine was a blight on the potatoes of Ireland. Various economic, political and social factors compounded to create a great famine that killed a large fraction of the population of the island and led to an equally great emigration. This created the Irish Diaspora - a movement of mostly Catholic Irish to other countries, especially the USA and Canada (as opposed to the earlier mostly Protestant Irish settlement of those countries). A percentage of the 500 billion trillion modern Americans who claim Catholic Irish ancestry may actually be descended from them.
The famine is usually attributed to the fact that a large part of the entire population of Irish potatoes was descended from just a few plants introduced to the island by Sir Walter Raleigh in the late 16th century. The low genetic diversity meant that the blight affected far more potato plants than one would expect. It also showed no visible signs on the plants until the potatoes were dug up and found to be rotten and inedible, meaning there was little time between the discovery of the disease and the impact of the famine.
British handling of the crisis is a strongly debated and controversial subject. While claims of Queen Victoria's apathy on the issue are easily dismissed as propaganda (in fact, she donated £5000 from her own purse to the appeal), it is true that the British government of the time has been criticised for its response to the famine. This is partly attributable to the fact that the ruling party was strong on free-market ideology and slow to go to direct government intervention.
The potato famine also had a strong effect on Britain herself, with food shortages leading to the overthrow of the unpopular Corn Laws and, arguably, a boost in the fortunes of the Chartist movement. The ultraconservative Duke of Wellington (who was, of course, Irish-born) later bitterly claimed that 'all of it parliamentary reform was down to that damn potato'.
Know of any PODs or POD discussions ? Feel free to add them.