The Kings' Rebellion

An Imperial civil war started by several of the Kings of the Empire during the reign of the Emperor Adalbard .
The causes of the war were firstly the attempt by Adalbard to raise armies from the kingdoms to invade the Atlan Mountains to bring the Mountain Dwarves back into the Empire after they had declared independence from the Empire in anger at Adalbard's insults and secondly, Adalbard's insistence that his eldest son Clodoard succeed him.It may also be that Adalbard seduced the queen or daughter of more than one of his kings.
It was King Gundabar of Brugund who led the rebellion, and most of the kings of the Empire joined him. Adalbard was able to draw on support from lesser nobles - dukes and counts, and some of the elven princes.
The war lasted for three years. Both sides won victories but neither was able to press an advantage enough to conclusively win the war. But whereas Gundabar was a clever diplomat, Adalbard frequently annoyed his allies. One by one they withdrew their support. Seeing the direction that the conflict was going, the Emperor offered peace. 

The rebels demanded that Adalbard renounce the title of Emperor, but allowed him to remain King of Prunzinn. They also decided that in future, emperors would be decided by a vote of all the nobles of the Empire from kings to counts. This was the Grand Conclave. King Gundabar declared that he had no wish to be emperor. The first Grand Conclave elected Rustlin, Grand Duke of Grand Duchy of Lustbrau as the fifth emperor of the New Empire.