Geoffrey II Grenonat, Count of Rennes, (died 1084) married Bertha, daughter of Rivallon I of Dol

Rivallon I of Dol

Rivallon of Dol-Combourg was born to Hamo I, Viscount of Alet and Roianteline. He would enter marriage with Evrard, Count of Bretueil and Viscount of Chartres's daughter, Aremburga de Puiset. He died around 1065. In his lifetime, he rebelled against Conan II, Duke of Brittany with the aid of...

 and Aremburga de Puiset. Alongside Ralph of Gael, he revolted against Duke Hoel

Hoel II, Duke of Brittany

Hoel II of Cornwall was count of Kernev , from 1058 as Hoel V, and after his marriage to Hawise, Duchess of Brittany, in 1066, he became duke of Brittany...

. Geoffrey played a commanding role in the Breton Revolt, in which he and several others planned to restore the authority of his uncle Eudo of Penthièvre

Eudo of Penthièvre

Eudo of Penthièvre was the brother of Alan III of Brittany . Eudo had been loyal to his brother throughout his reign, but he subsequently spent many years trying to wrest ducal power in Brittany from his nephew and ward, Conan II...

. Significantly neither Eudo of Penthièvre nor his eldest son Geoffrey I Boterel took part in the Norman conquest of England

Norman conquest of England

The Norman conquest of England began on 28 September 1066 with the invasion of England by William, Duke of Normandy. William became known as William the Conqueror after his victory at the Battle of Hastings on 14 October 1066, defeating King Harold II of England...

. When Ralph of Gael fled from England to Brittany in 1076 Geoffrey was holding the castle of Dol against Duke Hoël

Hoel II, Duke of Brittany

Hoel II of Cornwall was count of Kernev , from 1058 as Hoel V, and after his marriage to Hawise, Duchess of Brittany, in 1066, he became duke of Brittany...

, together with his cousin Geoffrey I Boterel

Geoffrey I Boterel

Geoffrey I Boterel was a Breton noble and one of the leaders of the Breton Revolt. He was the son of Eudo of Penthièvre, younger brother of Alan III of Brittany. Eudo had been loyal to his brother throughout his reign, but he subsequently spent many years trying to wrest ducal power in Brittany...

. Hoël and William jointly invested Dol, but the siege was raised by Philip I of France

Philip I of France

Philip I , called the Amorous, was King of France from 1060 to his death. His reign, like that of most of the early Direct Capetians, was extraordinarily long for the time...

 and Fulk IV of Anjou

Fulk IV of Anjou

Fulk IV , called le Réchin, was the Count of Anjou from 1068 until his death. The nickname by which he is usually referred has no certain translation...

. Ralph of Gael probably joined the rebels, but the event has been seen as the result of William's support of Archbishop Juhel of Dol, a simoniac whose years of misrule had finally led to his deposition. William the Conqueror not only failed to reinstate Juhel - who took refuge in Normandy - he suffered a serious military defeat as well. However, Geoffrey Grenonat and Geoffrey I Boterel were loyal to Eudo's dreams until their respective deaths.