If the Nobles can send their Prince, with their support, the Escarten Kingdom would surely be defeated
The Empire even in shambles is still not something a neighboring Kingdom can defeat!
Escarten Kingdom might be hard to invade but if the Nobles were to put an effort, it was still possible to succeed
After all, the Empire has the largest land in the continent while the Escarten Kingdom is tiny even for the standards of a Kingdom
As long as the Nobles invests in ships, with the number of soldiers their combined might has, they would definitely succeed
Not to mention, aside from the personal soldiers of the Nobles, there is also the Imperial Knights that would be mobilized along with the magicians of the Tower and the healers of the Temple!
This is something that would earn their chosen Prince meritorous deeds that would be enough as a foundation to turn them into the next Emperor