At the beginning of the 1800s, the population of Ireland stood at about five million. In the first 40 years of the century the population increased to about eight million. Many people lived in extreme poverty. In 1845 a fungus affected the vital potato crop in southern England, which soon spread to Ireland. With the failure of the potato crop, people began to die in their thousands either from hunger or disease. The famine came to an end after 1849 when the potato crop only partially failed. By then the population of Ireland had been reduced to just over six million by famine and emigration.
Fact file
When Ireland's potato crop failed, people dug up their crops only to find them rotting in the ground. Other picked what looked like sound potatoes, but they simply went rotten later on.
resources: tell me why (Chancellor Press)
image 1: https://www.irishcentral.com/uploads/article/123455/cropped_irish_famine.jpg
image 2: https://www.historyireland.com/wp-content/uploads/2013/02/A-Non-Famine-History-of-Ireland-2.jpg