In 1031 Agnes was mentioned as being at the court of her brother, Guillaume 'the Fat', and in 1036 and 1037 she was in a cloister together with her brother's wife, Eustacia, because Guillaume had lost his position in Aquitaine. In 1042 she was in Besanton at the court of her uncle Reginald when Bruno, Bishop of Wuerzburg, came to ask her hand in marriage for the widowed Emperor Heinrich III. In October 1043, at the Burgundian border, Agnes and Heinrich III met and travelled together to Mainz for her coronation. A month later they married with great pomp in Ingelheim. In 1046 they went to Italy and were crowned Emperor and Empress by Pope Clemens II. 
Heinrich III and Agnes became the parents of five children. Agnes  was usually with her husband and is mentioned in many imperial documents, yet she had no political influence on her husband. However, she did act as regent for her son, Heinrich IV, when her husband died in 1056. From 1056 until 1062 she tried, as regent, to preserve the Empire and continued Heinrich III's policies. 

She travelled the Empire extensively but her regency was troubled by some of the nobles she had trusted. She had placed Rudolf von Rheinfelden in charge of Swabia and betrothed him in 1059 to her eldest daughter, Matilda. A year later Matilda died and Rudolf became one of her son's rebellious vassals. In 1060 she sent an army to assist her son-in-law, Salomon of Hungary, but the army was defeated and Salomon and his wife were forced to flee. 
Her regency came to an abrupt end when the Bishop of Cologne kidnapped her son, Heinrich IV, and took over the regency. Without objection she returned to her own lands. In 1063 she went to Rome where she was befriended by Pope Alexander II who used her several times as an ambassador to the imperial court. She was also associated with Hildebrand, the future Pope Gregory VII. Agnes sided with the papal party and tried to conciliate between Pope Gregory VII and her son, Emperor Heinrich IV. 
 
 

Source: Leo van de Pas