Irish potato famine
In the 19th century, the potato was an indispensable food. In 1845, blight (a parasitical mould) contaminated potato crops, leading to a famine with considerable loss of life in Ireland, where almost a million people died over the course of a decade. At the same time, the English decided to expel the peasants from their land because they were no longer able to pay their land taxes. The famine and the expulsions fuelled a massive wave of Irish emigration, with around two million people leaving the island, mostly for the United States and Canada. The potato blight-induced famine also impacted Northern Europe as a whole.