"How about war supplies?"
"War supplies!" The envoy scoffs in annoyance, only to calm down a moment later. "King Salus said it will be better to come back with anything I can get rather than empty-handed. Sure thing, war supplies it is. I hope that will be enough."
After he leaves, your courtiers murmur and discuss that mayhaps the Duchy will get involved in bloody mess once again.
You retreat to your chambers where you write the letter of explanation to King Eón. You seal it and give it to your fastest messenger.
985 AD, Late Spring
The Dahnian envoy is back, along with your messenger. Where you charismatic enough in your writing? Did the messenger get there in time?
2
"Greetings, Grand Duke. Our master, King Eón, has heard my report and has read your letter. He has made a decision, which is as follows." He cracks open a scroll sealed with the wax seal of Dahnian royal family.
"Grand Duke Estwalf! You're hereby summoned to the capital of Dahnia, where you shall explain yourself before King Eón personally, and the charge laid against you is conspiracy with enemies of Dahnia. You may decline this summon; in that case, you will be removed from the office of Grand Duke of Tven, and the Electoral Council will decide the next Grand Duke. Your son Atan is of age and is your designated heir, therefore his candidature will be viable, and King Eón promised to not deny your son a chance to succeed you." The Dahnian envoy rolls up the scroll and looks at you, as your courtiers murmur, shout and bemoan this absurd injustice.
"What is your response, Grand Duke?"
A) "I will respond to the summon of King Eón, and explain myself to him!"
B) "I decline the summon, and my son Atan will sure show before the Council."
C) "I decline the summon!" Call the guards to imprison the envoy while you declare independence of Tven!