During the early years of the 19th century, famine was a common occurrence, particularly where population pressure was a problem. The population of Ireland grew to over eight million people prior to the Irish Famine (or Great Famine) of 1845–47. The Irish people depended on the potato crop for their sustenance. Disaster struck in August 1845, when a killer fungus (later diagnosed as Phytophthora infestans) started to destroy the potato crop. When widespread famine struck, about a million people died and a further million left the country. People died in the fields of starvation and disease. The catastrophe was particularly bad in County Mayo, where nearly ninety per cent of the population depended on the potato as their staple food. By 1848, Mayo was a county of total misery and despair, with any attempts at alleviating measures in complete disarray.