The counts of Nantes were originally the Frankish rulers of the Nantais under the Carolingians and eventually a capital city of the Duchy of Brittany.
Carolingian rulers would sometimes attack Brittany through the region of the Vannetais, making Nantes a strategic asset.
The control of the title by the Breton dukes figured prominently in the history of the duchy.
That uprising presented an opportunity for King Henry II of England to attack the Breton duke.
In the treaty ending their conflicts, the Breton duke awarded the county to Henry II.