Rain Emperor was swift in his decision, issuing an imperial decree to pass the throne to the Seventh Prince. As for the Eldest Prince and the Third Prince, they were relocated to the border garrisons, and their lands were taken back; it was obvious that they were going to die of old age outside the walls, never to return to the Imperial Capital in this lifetime.
This suited Rain Emperor's assertiveness; even if it were his own son, he'd either not intervene or go all out.
The Eldest Prince and Third Prince thus withdrew from the Rain Country's political stage. No matter how overwhelmingly influential they were before, in front of the emperor's power, they were so fragile that they no power to retaliate—they couldn't even bargain or find a quiet place to grow old.