The "beloved disciple," as Jesus had called him (John 13:23), was the youngest of the twelve apostles. Probably no more than 18 years of age at the time of Jesus' call to him, John belonged to the inner circle of the three (with James and Peter; Luke 9:28). He and his brother James were "sons of thunder" (Mark 3:17) who boldly proclaimed Jesus as the Messiah to the Jewish people. After Jesus' death and resurrection, he gave oversight to the churches of Asia Minor for many years and became known as the "elder" of these churches. He was the mentor of Polycarp, bishop of Smyrna, who later died as a martyr. In his later years John penned his Gospel, three short epistles for the churches of Asia, and the Revelation of Christ as the coming judge and ruler of the world. John outlived all the original 12 apostles, as well as Paul, dying about 96 AD.