St. Sebastian is a erly christian saint and martyr. He was born on 256 AD in Gaul France (under tradition). Not much is known about his early life.
In 283, Sebastian entered the army in Rome under Emperor Carinus to assist the martyrs. Because of his courage he became one of the captains of the Praetorian Guards under Diocletian and Maximian, who were unaware that he was a Christian.
Marcus and Marcellian, twin brothers, were imprisoned while serving as a Praetorian officer, for failing to make public sacrifices to the Roman gods. The brothers were christian church deacons. Their parents visited them during their incarceration, to implore them to renounce Christianity. St. Sebastian however persuaded both parents to convert to Christianity. St. Sebastian converted many others as well including the local prefect.
That led to his discovery and in 286 he was reported to Emperor Diocletian as a Christian. The Emperor, already notorious for ordering the executions of hundreds of Christians, scolded Sebastian and ordered him to be killed by making him bound to a stake in a training field and used as a target practice.
Archers riddled with arrows over his body. St. Sebastian, believed to be dead, left his body for burial and retrieval. Irene of Rome, whose Christian husband served Diocletian and also was martyred, recovered him. Irene discovered Sebastian was still alive, hiding him and nursing him back to health.
Once well Sebastian went to ambush him in pursuit of Diocletian. He managed to trap Diocletian by a stairwell and continued to loudly and publicly condemn him for his persecution of the Christians. Diocletian was immediately taken aback, surprised that Sebastian was still alive but recovered his composure. He would not allow Sebastian, with his life, to escape this time.
He ordered his former guard to be beaten to death with clubs, then thrown into the sewers.His body was recovered by a Christian woman, named Lucina, and she secretly buried him in the catacombs beneath Rome. He died on 288 AD.