The youth, it would seem, followed his father's example in joining the army soon after his coming of age. He proved to be a charismatic soldier and consequently rose quickly through the military ranks of the time. By his late twenties he had gained the titles of ''Tribunus'' (Tribune) and later ''Comes'' (Count). By that time George had been stationed in Nicomedia as a member of the personal guard attached to Roman Emperor [[Diocletian]] (reign 284–305).
In 303, Diocletian issued an edict authorising the systematic persecution of Christians across the Empire. His
successor, the emperor Galerius, was supposedly responsible for this decision and would continue the persecution during his own reign (305–311). It is believed that George was ordered to take part in the persecution but instead confessed to being a Christian himself and criticised the imperial decision. An enraged Diocletian proceeded in ordering the torture of this apparent traitor and his execution.
Then, after innumerable forms of torture, George was executed by decapitation in front of Nicomedia's defensive wall on April 23, 303. The witness of his suffering convinced Empress [[Alexandra the Empress|Alexandra]] and Athanasius, a pagan priest, to also become Christians, and so they also joined George in martyrdom as consequence. George's body was then returned to Lydda for burial, where Christians soon came to honour George as a martyr.