The malcontents spread the most odious scandals about her.

It so happened that one of the most considerable amongst the great vassals of France, Theobald IV., Count of Champagne, a brilliant and gay knight, an ingenious and prolific poet, had conceived a passion for her; and it was affirmed not only that she had yielded to his desires, in order to keep him bound to her service, but that she had, a while ago, in concert with him, murdered her husband, King Louis VIII.

In 1230, some of the greatest barons of the kingdom, the Count of Brittany, the Count of Boulogne, and the Count of St.Pol formed a coalition for an attack upon Count Theobald, and invaded Champagne.

Blanche, taking with her the young king her son, went to the aid of Count Theobald, and, on arriving near Troyes, she had orders given, in the king's name, for the barons to withdraw: "If you have plaint to make," said she, "against the Count of Champagne, present before me your claim, and I will do you justice." "We will not plead before you," they answered, "for the custom of women is to fix their choice upon him, in preference to other men, who has slain their husband." But in spite of this insulting defiance, the barons did withdraw.

Five years later, in 1235, the Count of Champagne had, in his turn, risen against the king, and was forced, as an escape from imminent defeat, to accept severe terms.
An interview took place between Queen Blanche and him; and "'Pardie, Count Theobald,' said the queen, 'you ought not to have been against us; you ought surely to have remembered the kindness shown you by the king my son, who came to your aid, to save your land from the barons of France when they would fain have set fire to it all and laid it in ashes.' The count cast a look upon the queen, who was so virtuous and so beautiful that at her great beauty he was all abashed, and answered her, 'By my faith, madame, my heart and my body and all my land is at your command, and there is nothing which to please you I would not readily do; and against you or yours, please God, I will never go.' Thereupon he went his way full pensively, and often there came back to his remembrance the queen's soft glance and lovely countenance.