(Ed's note: this essay details a brief description of the famine, the causes, and areas when the famine had greatest impact. There is so much text about the famine on the web, I thought I would keep this short. The Crummy family resided in Ulster, probably around Belfast, where the famine had minimal effect.)
It began with a blight of the potato crop that left acre upon acre of Irish farmland covered with black rot. As harvests across Europe failed, the price of food soared. Subsistence-level Irish farmers found their food stores rotting in their cellars, the crops they relied on to pay the rent to their British and Protestant landlords destroyed. Peasants who ate the rotten produce sickened and entire villages were consumed with cholera and typhus. Parish priests desperate to provide for their congregations were forced to forsake buying coffins in order to feed starving families, with the dead going unburied or buried only in the clothes they wore when they died.
Landlords evicted hundreds of thousands of peasants, who then crowded into disease-infested workhouses. Other landlords paid for their tenants to emigrate, sending hundreds of thousands of Irish to America and other English-speaking countries. But even emigration was no panacea -- ship owners often crowded hundreds of desperate Irish onto rickety vessels labeled "coffin ships." In many cases, these ships reached port only after losing a third of their passengers to disease, hunger and other causes. While Britain provided much relief for Ireland's starving populace, many Irish criticized Britain's delayed response -- and further blamed centuries of British political oppression on the underlying causes of the famine.
The Irish Famine of 1846-50 took as many as one million lives from hunger and disease, and changed the social and cultural structure of Ireland in profound ways. The Famine also spurred new waves of immigration, thus shaping the histories of the United States and Britain as well.
The combined forces of famine, disease and emigration depopulated the island; Ireland's population dropped from 8 million before the Famine to 5 million years after. If Irish nationalism was dormant for the first half of the nineteenth-century, the Famine convinced Irish citizens and Irish-Americans of the urgent need for political change. The Famine also changed centuries-old agricultural practices, hastening the end of the division of family estates into tiny lots capable of sustaining life only with a potato crop.
There were several distinct kinds of agriculture present in Ireland at the time of the famine. The farmers in the east depended upon cereal crops, while those in Ulster grew flax. Only in the small farms of west of Ireland, and in parts of Munster, was the potato in a monopolistic position. It is estimated that at the eve of the famine 30% of Irish people were largely or wholly dependant on potatoes for their food. Thus, when the Blight struck it was these people who had nothing to fall back on. In Connaught some have estimated that as many as 25% of the population died.
Those who lived nearer to large cities had more access to imported goods. Although food was exported as usual from Leinster in 1844 and 1845, there was a net import of almost a million tons of grain by 1847. However, these imports naturally reached those nearer to the cities and these are in the east and south. Dublin, Belfast and Derry escaped with almost no effects at all, while Cork and Wexford were relatively better off than their rural environs. It was the inland and especially the western areas that could benefit least from the food of the cities. Given the fact that potatoes are notoriously hard to transport in any case, it would be difficult to get potatoes to Connaught even in a non-famine situation.