In his youth, Ireneaus was a disciple of Polycarp, who was a disciple of the apostles, who sent him to preach in Gaul. Following the martyrdom of St. Pothinus, Ireneaus was installed as bishop. In his countless writings, Ireneaus defined the Orthodox Faith and also defended it from heretics. Ireneaus was martyred for Christ in the time of Emperor Severus in the year 202 A.D., as were also nineteen thousand of his fellow Christians.