How about this.

The mighty Dragonborn of the 4th era has defeated Alduin and has ended the civil war between the Stormcloaks and the Imperial Legion. There was peace for many years, both General Tullius and Ulfric Stormcloak are dead. When suddenly, the Dragonborn is out hunting dragons, and is "lost" for unknown reasons.
With his/her influence on the country of Skryim now gone, the Stormcloak and Imperial soldiers once again wage war. Seeming to be in a weakened state, Hammerfall and High Rock unnexpectadly join forces under the Hammer Rock Empire, and invade Skyrim. Feeling the need to protect Skyrim, Morrowind attacks the Hammer Rock Occupied Skyrim, desperatly trying to push the enemy out of their neighbor's home. Noticing the ongoing wars, Black Marsh leaves the Imperial Legion. Angered by their loss of land, Cyrodill desperatly spreads out and invades Black Marsh, Elsweyr, Valenwood, Hammer Rock, Skyrim, and Morrowind.

Angered by their stupidity of war, Akatosh plans to wipe out all the races of mer, men, and beast folk, by invading Nirn with his army of the Divines.

the future Champion of Nirn is a prisoner in Hammer Rock occupied Skyrim, being sent to execution for unknown reasons. When right before his execution, an army of spirits attack (later to be revealed as the Army of the Divines), being the only survivor, he is the only one who knows of Akatosh's plans. the Champion then embarks to find the only one who can convince the lands to unite, the Dragonborn.

about halfway through the main quests, the Champion meets Akatosh and discovers of the Dragonborns fate, he/she has been killed, by Akatosh in the form of a dragon. After a short battle, Akatosh reveals to the Champion that this was his plan all along, to cause war in the land, and wipe out the races, so that better ones can replace them. He then knocks the Champion off of a cliff.

Luckily, the Champion had landed ona ledge, and survived as Akatosh flew away. With a new goal, the Champion travels to each country to try to end the wars. Along the way he meets the graybeards, and masters the Thu'um. When questioned, they say he is not full Dragonborn. Somehow, during his battle with Akatosh, he was partly infused with the soal of a dragon as he got hit by him. Making him a demi-Dragonborn, mastering the Thu'um but not able to absorb dragon soals.

In the end, the Champion is succesful in uniting the lands under the single banner of Tamriel . and using his knowledge of the Thu'um, shouts into the sky a challenge against Akatosh. Akatosh then freezes time, and meets the Champion. After a long duel, the Champion eventually forces Akatosh to yield, who then states how the races had deemed themselves worthy. Unfreezing time, he allows the races to all live, and the new country thanks him, deeming him Champion of Tamriel. However, other continents recognize his heroism, and he is soon Champion of Nirn.

Tamriel is then again divided into the old countries, but they are no longer at war and united as the new Tamrielic Empire.