Baptism of Boris I; 864. Boris I (852-888) is memorable in the history of Bulgaria; for he was the first ruler to become a Christian; and made his people adopt Christianity. His baptism took place in 864; and the Byzantine emperor Michael III acted as sponsor. He decided later in favour of the Eastern Church of Constantinople against the Western Church of Rome. Illustration for Hutchinson's History of the Nations (Hutchinson; c.1920). Note: Image has been digitally enhanced to facilitate repro.