Eusebius of Caesarea

Bishop of Caesarea and the 'Father of Church History,' Eusebius wrote the Ecclesiastical History, which traces Christianity from the apostolic age through the early fourth century. His work preserves countless fragments of lost early Christian writings that would otherwise be unknown. He was a close advisor to Emperor Constantine and played a key role at the Council of Nicaea (325 AD). His chronicle of martyrdoms, theological controversies, and the spread of the gospel remains the foundational source for understanding how the early church grew from a persecuted sect to the religion of the Roman Empire.