Article snapshot taken from Wikipedia with creative commons attribution-sharealike license.
Give it a read and then ask your questions in the chat.
We can research this topic together.
Bertha of Cornouaille (fl. 1125–56), also known as Bertha of Brittany (Breton: Berthe Breizh), was the Duchess of Brittany between 1148 until her death and Dowager Countess of Richmond. Bertha was the elder daughter of Conan III of Brittany by Maude, the illegitimate daughter of King Henry I of England. She was the last member of the Breton house of Cornouaille to reign over Brittany.
Life
Bertha was the daughter of Duke Conan III of Brittany. She married the son of Stephen of Treguier, Alan the Black, and she lived in England with Alan until his death in 1146. Alan would eventually become Earl of Richmond. On his deathbed, Conan III renounced Bertha's brother Hoel as heir and designated Bertha as his heiress, Duchess of Brittany.
Family
In her first marriage, by 1138, Bertha was married to Alan the Black.
Everard states Odo and Bertha had only one daughter, Adelaide.
War broke out between Bertha's son Conan IV, Duke of Brittany and her second husband Odo. Odo may have made a compact with his brother-in-law, Hoel of Nantes, to divide Brittany between them. However, in late 1156 Conan IV was able to defeat Odo and secure his maternal inheritance.
Bryan, Elizabeth J. (2016). "Matthew Parker and the Middle English Prose Brut". In Rajsic, Jaclyn; Kooper, Erik; Hoche, Dominique (eds.). The Prose Brut and Other Late Medieval Chronicles. York Medieval Press.
Dunbabin, Jean (1985). France in the Making, 843-1180. Oxford University Press.
Everard, J. A. (2004). Brittany and the Angevins: Province and Empire 1158–1203. Cambridge University Press.
Vincent, Nicholas (2007). "The Court of Henry II". In Harper-Bill, Christopher; Vincent, Nicholas (eds.). Henry II: New Interpretations. The Boydell Press.
Warren, Wilfred Lewis (1977). Henry II. Yale University Press.
Bertha, Duchess of Brittany House of CornouailleBorn: c. 1114 Died: 1156