Before baptism he was a renowned military commander under Trajan. While hunting in the woods, he met a great stag with a shining Cross between his antlers. Through the stag, the Lord spoke to Placidas (his pagan name) and told him to find a priest and be baptized into Christ.
Returning home, he found that his wife Tatiana had also had a vision in which she was told to become a Christian. They were baptized, Placidas receiving the name Eustathius, and Tatiana the name Theopiste; their two sons were baptized with them. Eustathius and his family were almost immediately subjected to a series of grievous trials, in which all were separated from one another.
After years of hardship they were re-united, and returned to Rome with honor when the Emperor sought out Eustathius to command his army once again. But when the Emperor Hadrian (who had succeeded Trajan) commanded them to worship the idols, all of them refused. They were put together into a large bronze ox which was heated white-hot in a fire. When their bodies were removed, they were found to be dead but intact.
The Prologue concludes, ‘Thus this glorious general gave to Caesar that which is Caesar’s, and to God that which is God’s, and entered into the eternal Kingdom of Christ our God.’