It was her formidable grandmother, Queen Eleanor of England, who took her to France to be married to its crown prince who, twenty-three years and ten children later, became King Louis VIII. However, after only three years Louis VIII died and Blanche became Regent for her son, the new King Louis IX, until 1234. 

In 1236 in London she attended the marriage of King Henry III to Eleanor de Provence. Together with her son she brought from the east the reputedly Holy Cross from Christ's crucifixion to Paris and they built the Sainte Chapelle to house it. In 1248 Louis IX went on crusade and Blanche again became Regent. In 1250 news reached her that Louis IX had been captured and she rewarded the messengers by having them hanged. 

When the Pastoureaux uprising in 1251 reached Paris, she at first held talks with its leaders but then imprisoned them and put them to death. She herself died in 1252. 

Source: Leo van de Pas