On 9 October 1246, Adelaide married
John I of Avesnes,
Count of Hainaut. Like her mother, she was a patron of religious houses. Her religious interest is reflected in that three of her sons became bishops, and her one daughter became an abbess. She also insisted on a bilingual education for them. Between 1258 and 1263, Adelaide was
regent of Holland in the name of her nephew
Floris V. She called herself Guardian of Holland and Zeeland (Tutrix de Hollandie et Zeelandie). After he came of age, she continued to advise him. She died in 1284 at
Valenciennes, but in 1299, with the death of Floris' son
John I, it was her own son John II who inherited Holland through her. She gave
Town privileges to
Schiedam, which afterward had the right to be called a city. In it, she founded
Te Riviere Castle, which was then the second-largest castle in
Holland. She ordered the construction of the
Schielands Hoge Zeedijk, which today continues to protect 3 million inhabitants in a wide area around Rotterdam.
Jacob van Maerlant dedicated his first poem,
Geesten, to Adelaide. == Issue ==