The cause of the Irish Potato Famine in the mid-19th century was primarily a devastating potato blight known as Phytophthora infestans, which destroyed potato crops across Ireland, the staple food for much of the population. Alongside this agricultural disaster, social and economic factors exacerbated the situation. British policy, including export-focused economic practices and inadequate relief efforts, led to widespread starvation and suffering. As a result, approximately one million people died, and another million emigrated, significantly reducing Ireland’s population. The famine also intensified Irish nationalist sentiments and highlighted the consequences of British colonial rule, reshaping Irish society and politics.