How about striking preemptively?
At the moment, Jiang Pengji had occupied the entire Fengyi County. With 20,000 carefully trained troops in hand, come next spring, she could conquer Wanzhou and claim all of Wanzhou as hers. Then she could simply send a memorandum to the throne and force the royals of Dongqing to bestow the title State Governor of Wanzhou upon her.
If she were to deploy her troops to traverse half of the northern lands to attack Huang Song and strangle her enemy in his cradle, she wouldn't be able to conquer Wanzhou next year. But the advisors in Jiang Pengji's camp also felt annoyed at the thought of leaving Huang Song to further develop his influence at the borders of the northern and southern kingdoms.
Feng Jin said, "It's best if we discuss the matter with our lord."