Random argument on a Monday morning

So... I'm drinking my coffee, reading the news, sifting through emails, and half listening to a pal of mine when I catch the words, "the potato famine was one of the most important events in history."

To prove a point, I was wondering how many of you could tell me (without Googling it):
1) When the potato famine occurred?
2) What WAS the potato famine?
3) Whether or not you believe it was one of the top 25 events in all of history.