In the second or third century when st Patrick was alive, the Roman Empire had just fallen. The people of the fallen empire did not know it had just fallen though. The Catholic Church ran the schools. At that time, Patrick was born into a rich family. He was the second born son which meant he had to go to the military or the church. Patrick chose the Church. The hooding ceremonies at school started at that time. Males were the only ones allowed to go to the schools so they became monks. This is why they got hooded.
Patrick was in the abbey when it got raided by Vikings. He was kidnapped and sold into slavery to a chieftain. The Vikings would steal the rich children and sell them into slavery wth their parents. The abbeys werte easy picking because they didn't fight back. The vikings grabbed him and the other monks adn sold him as farm serfvice to the other chieftains.
Immediately, St. Patrick got into converting all people to Christianity. This made the chieftains mad because Patrick was making fun of the indigenous people. At the time the religion was Wicca, presently known as witchcraft. It was a religion that honored mother earth on many levels. Male and female were in their priesthood. Due to the bastardization of Constantine,who hate women, they changes the Bible to suggest women's power was evil. Patric took that stand to ban Wicca in his lectures. He said Wicca was an arm of the devil. The chieftain wanted to execute him, but the chieftain's daughter talked him into exiling him form Ireland instead.
St. Patrick went to Gaul to find the bishop and tell him he found a new peole to colonize. He didn't follow the custom of hugging the captain to get a free ride. Instead he beat the captain up, stole the boat and whent to Gaul. The bishop at that time was impressed. He gave him troops and promoted him from a monk to a priest so that he could legally convert people and baptize them as Christians.
With a boat and about 100 mecenaries from the bishop, he returned to Ireland. With teh mercinaries, he went to ireland and converted people through force. All leadership of the indigenous religion was destroyed or exiled from the island. The new form of Christianity was bastardizd from the original Christianiy into a more COnstaninized version where women were inferior and men were superior. This was different from the indigenous religion where women had the equal right to vote. Some women were chieftains at this time too. And in some parts of their religion, women were considered superior, for example when speaking about mother earth.
The killing of these people were mythologized by saying the snakes were driven out of Ireland. If you do not believe this story, do your own research. This was the continuation of colonization that started with Romans.