As the royal family of Demacia for centuries, members of the Lightshield line have spent their lives waging war against any who opposed Demacian ethics. It is said that every Lightshield is born with anti-Noxian sentiment in his blood, and Jarvan IV is no exception.
As his forefathers had before him, he led Demacian troops into bloody engagements with Noxian forces, and on many occasions he has bled alongside wounded allies and fallen comrades. His most crushing defeat came at the hands of, where he was outmaneuvered and captured by a Noxian battalion. This mistake nearly cost him his life at the hands of , but he was rescued by the Dauntless Vanguard, an elite Demacian strike force led by Jarvan's childhood companion, .
Those close to him believed that his capture changed him.was quoted as saying: "His eyes never seemed to look at you, only through you to something he could not look away from."
One day, without warning, Jarvan IV hand-picked a squad of Demacian soldiers and left Demacia, vowing to find 'atonement'. He began by tracking and hunting the most dangerous beasts and bandits he could find in northern Valoran, but he soon tired of such prey. Seeking something that only he understood, he ventured south of the Great Barrier. He wasn't heard from again for nearly two years.
After many had assumed the worst, he returned to glorious fanfare on the streets of Demacia. His Demacian plates were adorned with the bones and scales of creatures unknown. His eyes bore the wisdom of someone twice his age. Of the twelve soldiers who had departed with him, only two returned. In a tone as cold and steady as steel, he swore to bring the enemies of Demacia to their knees.