Patrick of Ireland

Patrick was kidnapped by Irish slavers as a teenager, escaped, and went back as a missionary to the people who enslaved him. His Confession is the earliest substantial document from Christian Ireland and one of the earliest first-person accounts of any missionary anywhere. The conversion he led was bloodless, organised through monasteries rather than imperial power, and produced a Christianity literate enough to send missionaries back across Europe. He is also the reason there are so many Irish saints — the model he set up made saint-production a cottage industry.