Career
In 1259, her great-aunt Margaret, married Richard of Neufchâtel-en-Bourgogne. As her dowry, she brought the Lordships of Blamont, Châtelot, Belmont, and Cuisance into the marriage. The Lords of Neufchâtel-en-Bourgogne placed Blamont under the protection of the Duke of Burgundy and thus detached it from Montbéliard.
In 1282, Guillemette married Reginald of Burgundy.
They had five children:
Othenin "the Mad" (d 1339), who succeeded her as Count of Montbéliard
Agnes of Montbéliard (d 1377), married Henry I, Count of Montbéliard, who inherited Montbéliard after Othenin"s death
Joanna (d 1347), married:
Ulrich III, Count of Pfirt
Rudolf Hesso, Margrave of Baden-Baden
William, Count of Katzenelnbogen
Margaret, married William of Antigny, Prince of Sainte-Croix
Adelaide, married John II, Count of Chalon-Auxerre
In 1283, her great-grandfather, Theodoric III, Count of Montbéliard (1205–1283) died. Theobald III of Neufchâtel, who was a grandchild of Theodoric III and who wanted Montbéliard for himself, conspired with Reginald"s brother Otto IV to have Montbéliard recognized as a fief of Burgundy.
To resolve this, Reginald ceded Blamont and Châtelot to Theobald.
