St. Sebastian was born into a wealthy Roman family, and was educated in Milan. He became an officer of the imperial Roman army, eventually becoming promoted to Captain of the Guard and earning the favor of Emperor Diocletian. 

While Diocletian was persecuting Christians, Sebastian was visiting them in prison, bringing supplies and comforting them. He is said to have healed the wife of a fellow soldier by making the sign of the cross over her. Sebastian converted many soldiers, and a governor, while serving in the army. 

In 288, Sebastian was accused of being a Christian. He was tied to a tree, shot with arrows, and left for dead. Sebastian survived this attack, and when he had recovered, he returned to Rome to try to convert Diocletian. The emperor had him beaten to death.