Juliane was born at Dillenburg Castle[1] on 3 September 1587[1][note 1][3][4] as the fifth child and second daughter of Count John VII the Middle of Nassau-Siegen and his first wife, Countess Magdalene of Waldeck-Wildungen.

The marriage of her eldest stepbrother, Count Philip Louis II of Hanau-Münzenberg, to Countess Catherine Belgica of Nassau, a daughter of Prince William I the Silent of Orange, was also celebrated here in 1596, a festive highlight of Juliana's childhood.

Soon after his marriage, the Landgrave of Hesse-Kassel was considered in imperial politics as a protagonist of the Calvinist cause, alongside the Electoral Palatinate, who also belonged to the relatives of the House of Nassau.

When the estates independently entered into negotiations with Tilly to obtain the withdrawal of the troops of the Catholic League or at least a reduction in the war burden, Maurice accused them of treason.

She stood up for the Calvinists in the county of Nassau-Siegen who suffered from the recatholicisation attempts of her brother John VIII the Younger, who had converted to the Catholic Church and was in Spanish service.

[6] Juliane was able to put her interest in state administration into practice after she had gained the relevant knowledge in the Rotenburger Quart, which she initially managed together with her eldest son Herman.

Faced with the threat of war, Juliane again sought brief shelter at Kassel Castle in 1631 and then lived until her death in the Nassauer Hof at the River Fulda, later called Packhof vor der Schlagd, which Maurice had already given her in 1617.