Edgar Rice Burroughs 
The Mad King [EPUB ebook] 

I
A RUNAWAY HORSE
All Lustadt was in an uproar. The mad king had escaped. Little knots of excited men stood upon the street corners listening to each latest rumor concerning this most absorbing occurrence. Before the palace a great crowd surged to and fro, awaiting they knew not what.
For ten years no man of them had set eyes upon the face of the boy-king who had been hastened to the grim castle of Blentz upon the death of the old king, his father.
There had been murmurings then when the lad's uncle, Peter of Blentz, had announced to the people of Lutha the sudden mental affliction which had fallen upon his nephew, and more murmurings for a time after the announcement that Peter of Blentz had been appointed Regent during the lifetime of the young King Leopold, "or until God, in His infinite mercy, shall see fit to restore to us in full mental vigor our beloved monarch."
But ten years is a long time. The boy-king had become but a vague memory to the subjects who could recall him at all.
There were many, of course, in the capital city, Lustadt, who still retained a mental picture of the handsome boy who had ridden out nearly every morning from the palace gates beside the tall, martial figure of the old king, his father, for a canter across the broad plain which lies at the foot of the mountain town of Lustadt; but even these had long since given up hope that their young king would ever ascend his throne, or even that they should see him alive again.
Peter of Blentz had not proved a good or kind ruler. Taxes had doubled during his regency. Executives and judiciary, following the example of their chief, had become tyrannical and corrupt. For ten years there had been small joy in Lutha.
There had been whispered rumors off and on that the young king was dead these many years, but not even in whispers did the men of Lutha dare voice the name of him whom they believed had caused his death. For lesser things they had seen their friends and neighbors thrown into the hitherto long-unused dungeons of the royal castle.