Is it true that St. Patrick commited genocide in Ireland?
No, that’s not even close to true. These claims come from two separate arguments, both of which are based either on invention or fantasy. The first of these claims is that St. Patrick committed a cultural genocide, where all aspects of Irish life were completely eradicated and replaced with Roman Catholic ideals, styles, and practices, which is a gross misunderstanding of both sociology and cultural conversion. In reality although it true that a large majority of the Irish people converted to Christianity, this did not mean that all aspects of Irish culture such as language, music, folklore, or art entirely disappeared but instead merely adapted to new social customs.
The second and more absurd theory is that before St. Patrick arrived in Ireland there was a group of Sub-Saharan African colonies within the island which had descended from the Twa people. These people are also supposedly the origin of the leprechaun and other mythical creatures and according to a number of websites it was St. Patrick who drove them out of Ireland, which is where the myth of him driving out the snakes also arose.