Never been any snakes in Ireland
Snakes is used as an euphemism for pagans or barbarians people who had different believes then Christianity
So he converted them to Christianity . When I think conversion I see children taken from there families to missionary schools and being brain washed , older people being tortured or even killed , But mostly I see people acting like they were converted but not really being converted. I'm sure there are even today some people who believe in the wheel of life , the tree of life , the old man of the forest and other pagan beliefs. Not all the snakes have left Ireland old Saint.Patrick missed a few.