Bertha of Burgundy

Bertha, Princess of Burgundy (952, 964 or 967 – 1010, 16 January 1016, or 1035) was the daughter of Conrad the Peaceful, King of Burgundy and his wife Matilda, daughter of Louis IV, King of France and Gerberga of Saxony. She was named for her father's mother, Bertha of Swabia.

She first married Odo I, Count of Blois in about 983. They had several children, including Odo II.

After the death of her husband in 996, Bertha's cousin Robert, co-King of France wished to marry her, in place of his repudiated first wife Rozala, who was many years his senior. The union was opposed by Robert's father, Hugh Capet, due to the close relation of husband and wife. However, the marriage went ahead after Hugh's death in October 996, which left Robert as sole king.

The closeness of Robert and Bertha by blood was such that Church authorities considered the marriage illegal. Accordingly, Pope Gregory V declared the pair excommunicate. This, and the lack of children (save one, who lived and died in 999), caused Robert to agree with Pope Silvester II to have the marriage annulled in 1000.

Robert went on to marry Constance of Arles. Bertha remained unmarried.