I've already written the intro for my 4th edition campaign in my homebrewed campaign world. It's a politically-charged, humanocentric storyline continued on from the 8 year campaign we've been running for a while now, although accelerated nearly 12 years into the future:
Act 1: Rise of King Verminas Belgarion
The stage upon which the war unfolds is a country known as Aglador. No stranger to strife amongst its kin, King Aden Ladros was branded a heretic by the Archbishop Blicard in 178 Third Age and died within the dungeons in the holy city of Mithrin Roel. Duke Verminas Belgarion ursurps the throne in Girithlin, the apparent victor of a political battle fought within the shadows. The death of Ethan Dautinthorne, the crown prince of Aglador, soon came thereafter due to malady. Over a period of eleven years, the newly-crowned King Verminas instituted vast political reformation and eliminated Aglador's monetary reliance upon the Southern Empire of Pharazon.
Aglador is thrown backward into a dark age.
In year 200, King Verminas Belgarion is suddenly stricken by malady (ironically, the same flux that had killed the crown prince) and dies in his ancestral home of Caer Moray. The question becomes who is to take the throne with no successor. Aurora Belgarion is the niece of Verminas, living as an adherent in Mahalma under the influence of the Olorinite Father Paramon. Prior to admittance, she was adopted by King Verminas as his daughter. This would make her the heir apparent, and when she was of age she would marry a man of the King's choosing. However, the Queen Elaine Belgarion unexpectedly became pregnant with a second son in 200, giving birth to Warren Belgarion. The newborn infant would ascend the throne by proclaimation from the Queen. Too young to rule, the crown prince required a male regent who would be king in all but name. Cassamir Dautinthorne, brother of the Queen, seemed the obvious choice for regency. However, fearing the influence such an appointment would give the Queen and the aristocracy, Parliament refused to back him. Instead, they recommend Duke Ethan Priam.
Act 2: War of the Two Dukes
Duke Cassamir Dautinthorne and Duke Ethan Priam are both distinguished; one the head of Iron Throne and master of Belegost and the other a folk hero and general of Rhovania's armies during the Border War II. Cassamir counts as ally to the greater part of the older aristocracy to the throne of Aglador, those that supported the rise of Balbanese Dautinthorne and his royal house during the Kinstrife. However, the disenfranchised and fallen nobility left in the aftermath of the second Border War look to Ethan Priam, a symbol of unification and strength amongst Dalefolk and Aradain alike.
Eventually, Aurora Belgarion is taken from Mahalma to the holy city and then turned over by the Knights of the Southern Cross to Duke Cassamir in Belegost. Casssamir then declares her the heir apparent to the throne, undermining the wishes of the Queen Elaine. Although marriage is rumored with Aurora to Cassamir or his son Balbanese Dautinthorne II, nothing has yet come to pass.
Although the lines have been drawn, it is not strictly between the Aradain and Dalefolk. The kidnapping of Aurora has precipitated the war with Duke Ethan, as he musters his soldiers along the edge of the Western Myrkwood, rallying loyal barons on his side.