3Theobald I (913 - 978), called the Cheat(er) or the Trickster (le Tricheur), was the first count of Blois, Chartres, and Châteaudun from 960, and Tours from 945.
Theobald was initially a vassal of Hugh the Great, Duke of France. Around 945, he captured King Louis IV to the benefit of Hugh. In return for freedom, the king granted him the city of Laon. He took the title of "count" in Tours. He seized Chartres and Châteaudun and remarried his sister to Fulk II of Anjou. In 958, he met Fulk in Verron and the two described themselves as "governor and administrator [of the] kingdom [of Neustria]" and comites Dei gratia ("counts by the grace of God").
Theobald's sister married Alan II of Brittany and Theobald governed the duchy during the minority of her son Drogo. Thus, Theobald extended his influence all the way to Rennes.
In 960, he began opposing Richard I of Normandy and entered into a long war with the Normans. In 961, he attacked Évreux. The Normans responded by attacking Dunois. In 962, he launched an assault on Rouen which failed. The Normans burned Chartres in response. He took control of the fortresses of Saint-Aignan in the Loir-et-Cher, Vierzon, and Anguillon in Berry.
During the minority of Hugh Capet, he reinforced Chartres and Châteaudun. Around 960, he built Saumur. By his death, he had built a vast power on the Loire, dominating central France.
His daughter Emma brought him the county of Provins, nucleus of the later county of Champagne.

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Europaische Stammtafeln Band II Tafel 42.

Married BEF 945 to Theobald I of Blois, Count of Blois
Child 1: , Odo I of Blois, Count of Blois, b. 950
Child 2: , Emma of Blois, b. CIR 950
Child 3: , Theobald of Blois
Child 4: , Hugo of Blois, Archbishop of Bourges