The great famine was important event in irish history because it

The Irish Great famine was is the period of food scarcity that hit Ireland between 1845 and 1850. The Irish were largely dependent on the potato harvest for their food supply. Ninety percent of them, however, had failed due to the potato disease. This pest was caused by the pseudo-fungus Phytophthora infestans and caused a real havoc to the monoculture. More than a million Irish people died as a result of the food shortage. Millions of others, either forced or otherwise, fled to North America, Australia, New Zealand and Great Britain.

Famine is another word for when food is scarce. Additionally, the Irish famine was one of the biggest famines is world history which is why it's important.