"I bow before his statue, unable to say goodbye to my friend and lord." — Lorekeeper Aeron
It's not often that a king was fatally defeated to the point of losing their entire country, gets to be venerated and celebrated for many years after that. King Icenus was the last big leader of the Avlans during the Sol invasion. He was considered to be the last hope against the sprawling empire. He managed to unite almost two thirds of the island and lead them in many battles against the Sol army. But ultimately, they all lost and his past allies were all punished one way or another, their families sent to exile.
King Icenus didn't fall in battle. During his defensive campaign he fell gravelly ill and many believe to this day that the spies of the empire managed somehow to get close to him and poison him and his best warriors. The sickness was so fast and so selective, it would be hard to believe all of that was trully a coincidence. Especially when none of the common soldiers got sick with the same symptoms, even the young squires serving the king were spared.
This is why, the fall of the Avlans to the Sol, is more seen as a tragedy and not as a failure of the noble chieftains not being able to defend their people properly. Much of that narrative is nowadays used when speaking about the knight serving the current king of Avalonia - nothing can defeat them, apart from treachery.
The body of the king was never recovered - it was smuggled away under a cover of the knight and buried somewhere deep in the mountains, with his many treasures and weapons, most notably his Gleaming Sword of Truth. Seeking any kinds of information about the last king and where he was laid to rest is seen with disgust among the locals as no one likes graverobbers dishonouring their brave king.