To know that in ancient times, the strength of military forces directly determined the strength of a nation. The one hundred thousand strong army in the hands of Eighth Prince was exactly what Lin Yi coveted the most.
If they rashly empty Yuquan Mountain now, Eighth Prince might very likely rise in rebellion.
Sun Tzu said, the best strategy is to subdue the enemy using strategy; next is to disrupt their alliances, then to defeat their forces, and the worst strategy is to attack their cities.
To deal with Eighth Prince, the best approach would be to first foil the enemy's strategic intentions through cunning, next to use diplomacy, then to use martial force to defeat the enemy, and the last resort is to attack the enemy's cities.
Nowadays, although the Emperor has reclaimed much of his power, it is still not absolutely stable.
Waging a war at this time would be highly disadvantageous for the Emperor. Moreover, it is always the common people who suffer from war.