Third person pov:
Father was blinded by jealousy. In the end all 23 of the other children died. Only father and uncle survive.
Even after then everyone agree that uncle was fit to be king and crowned him. At this point father was completely blind.
The first concubine used to opportunity to hire an assassin to kill uncle at his coronation day.
Father know of this and didn't stop the first concubine because he was also under the first concubine's manipulation.
Little did he know he made the biggest mistake in his life. Uncle was kind and brave.
He have long realised father's jealousy before even father himself has realise. He knew that the first concubine will take advantage of this.
From the beginning uncle decided to offer the throne to father on the coronation day.
And on the coronation day everyone was surprise when uncle announced that he will step down from the throne and handed it to father.