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. Their county served as a march against the Bretons of the Vannetais. Carologinian rulers would sometimes attack Brittany through the region of the Vannetais, making Nantes a strategic asset. In the mid-ninth century, the county finally fell to the Bretons and the title became a subsidiary title of the Breton rulers. The control of the title by the Breton Dukes figured prominently in the history of the Duchy. The title Count of Nantes was given to Hoel, a disinherited son of a Duke. He lost the Countship due to a popular uprising. 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 Countship of Nantes to Henry II.
---- – 778 Roland, as prefect of the Breton March - subject of the Chanson de Roland786 – 818 Guy, as prefect of the Breton March, successor to Roland818 – 831 Lambert I - exiled by Charlemagne and replaced by Ricwin.831 – 841 Ricwin -a comes of Charlemange, and fidelis of Louis the Pious, he opposed Nominoe in the founding of Redon Abbey841 – 843 Renaud843 – 846 Lambert II846 – 849 Amaury, imposed by Charles the Bald in opposition to Lambert II849 – 851 Lambert II (restored)852 – 860 Salomon de Bretagne861 – 866 Robert the Strong, also Count of Anjou866 – --- Hugh of the Breton March--- – --- Henry of the Breton March--- – --- Odo, the future Odo, King of West Francia, as the Marquis of Neustria886 – 896 Berengar II of Neustria as Margrave of the Breton March, later also Count of Rennes896 – 911911 – --- Robert, the future Robert I of France as the Marquis of NeustriaAlan I, King of Brittany ruled Nantes as King of Brittany until his death in 907.
907 - c 914 - vacant914 - 919 - Rognvaldr as leader of the Loire Fleet of Norway lands in Nantes; Robert of Neustria continues conflict with invading Vikings919 - Robert of Neustria cedes Nantes to Rognvaldr ? - 936 - Incon, Viking leader after the death of Rognvaldr936 - 938 - Alan Barbetorte returns to Brittany from England and engages the Vikings938 – 952 Alan I Barbetorte952 – 960 Drogo960 – 981 Hoël I981 – c.988 Guerech990 – 992 Conan I, Count of Nantes by conquest992 – 1004 Judicael1004 – 1038 : Budic1038 – 1051 : Matthew I1051 – 1063 : Judith (with Alain Canhiart)1054 – 1084 : Hoël II1084 – 1103 : Matthew II1103 – 1119 Alan II1119 – 1148 Conan II1148– 1156 Hoël III1156 – 1158 Geoffrey I FitzEmpress, younger brother of Henry II of England1158 Conan III, seized the County and Nantes before returning it to Henry of England1158 – 1185 Henry II of England, gained the county under his treaty with the Duke of Brittany1185 – 1186 Geoffrey II1185 – 1201 Constance1196 – 1203 ArthurThe County of Nantes was merged permanently into the Ducal crown of Brittany, and subsequently the crown of France, through Constance's descendants.