She, as well as her half sister Christina Gyllenstierna, her mother and her daughters, belonged to the Swedish noblewomen taken as prisoners by the Danes.
They were taken to Denmark in 1521 and imprisoned in the infamous Blaatornet (Blue Tower) in Copenhagen Castle - where she died of the plague in 1523, along with her two younger daughters Martha and Emerentia.
[1] Cecilia died the same year her son Gustav became king of the newly independent Sweden, which he had liberated from Denmark.
[2] There is no confirmation that this legend is true, however, though the women were said to have been badly treated in the prison by the cold air, harsh treatment and starvation.
[3] Her mother, her half sister Christina, and her eldest daughter Margareta were eventually released and returned to Sweden.