 Władysław I succeeded in re-uniting most of these lands back into the kingdom of Poland.Władysław I Łokietek was the oldest son of Casimir I of Kujawy ("Kazimierz I Kujawski") and his third wife Eufrozyna of Opole.He was third in seniority to be Duke of Kujawy, however, as he had two older half-brothers from Casimir's second marriage to Constance of Wrocław