The last and worst persecution of Christians in the Roman Empire was carried out by Diocletian in the 300’s. Thousands died for their faith. Saint Irenaeus was the bishop in what is present-day Yugoslavia. Irenaeus was born around the year 125. He knew Polycarp who had studied with the apostles. His writings began the foundations of Christian theology.
Irenaeus served as a priest under the first bishop of Lyon. He was not 
martyred during the persecution in Lyons. He wrote five books which explain how the heresy of the gnostics was different than the faith. Gnostics believe the world was made by an imperfect spirit.
In 304 he was brought before the governor of his province. He was told to sacrifice to the Roman gods or die. He was given the unusual sentence of being drowned in the city’s river. Saint Irenaeus complained it would be too easy of a death. He said he would like to suffer more for his faith. This angered the governor, who had Irenaeus beheaded and then his body was thrown in the river.