OTD 23 September 1158 Geoffrey II, Duke of Brittany

On September 23rd. 1158 a noble boy called Geoffrey was born. His parents
were King Henry II of England and Queen Eleanor of Aquitaine.

Legitimate Children of King Henry II of England - Geoffrey is the 5th from left

Geoffrey had a lot of famous brothers and sisters inter alia:

King Richard I 'The Lionheart'
Queen Eleanor
Queen Joan
Prince John

Geoffrey II, Duke of Brittany was named after his grandfather Geoffrey V of
Anjou.

Seal of Geoffrey II, Duke of Brittany

How did Geoffrey become Duke of Brittany? 

King Henry II of England was in war with Conan IV, Duke of Brittany.
In order to conquer the region, the daughter of Conan, Constance, had
to marry King Henry's son: Geoffrey.

When he was duke of Brittany Geoffrey started a revolt against his own
father King Henry II of England. He became a good friend with Prince
Philip of France.

Geoffrey also was known to attack monasteries and churches in order to
raise funds for his campaigns.

He died on August 19th (some sources spoke about August 21st.) 1186.
Constance and Geoffrey would have 3 children, one of them was born
after his death.