Your Highness! Now is your chance: Take Dragonclaw's land and push the separated armies back into the provinces of King Darkblood, before they have a chance to attack you from two sides.
Your Highness! Good! Now that you hold a province directly adjacent to King Darkblood's lands you don't have to deal with Sir Dragonclaw for now - if you manage to defeat the king, he will not pose much of a problem!