Her brother, Prince Willem II of Orange, arranged her marriage, hoping to achieve a reconciliation with the Friesian Nassau branch of his family and thus gain their support for his actions. However, when Willem II died at the age of twenty-four, her husband looked only at his own gain and not after the affairs of Willem II's posthumously born son.
Willem Frederik's selfishness caused a split in the Orange's political party, though he partly achieved his aim when Drente and Groningen elected him as Stadhouder. He was appreciated for his talents as an administrator but not for his character, and when he died in 1664 there was little bereavement.
As his widow, Albertine Agnes was Regent in Friesland, Groningen and Drente for her son, Hendrik Casimir II. Capable in adversity and the growing anti-Stadhouder feelings in The Netherlands, she at least produced stability in her territories.
In 1665 England and the Bishop of Munster declared war on The Netherlands. As the main provinces of The Netherlands, Holland, Zeeland and Utrecht had been without a Stadhouder since 1650. Also their armies had been neglected as the fleet was favoured. Count Johann Moritz of Nassau-Siegen was put in charge of the army but still the Bishop's army could not be stopped. Even the strongly defended city of Groningen was threatened and to give moral support, Albertine
Agnes hurried to the besieged city. Pressure by King Louis XIV of France, then an ally, forced the Bishop of Munster to withdraw.
Six years later, Louis XIV changed his mind and attacked the south of The Netherlands himself, while the Bishop of Munster together with the Bishop of Koln attacked the North. Albertine Agnes arranged the defence and suggested opening the dykes to flood the lands. Her moral support kept Johann Moritz of Nassau-Siegen going; and at last her nephew, Prince William III of Orange, was given his rightful position as Stadhouder.
During all these turbulent years, she also paid great attention to the education of her son and hoped to restore the unity between the two branches of her house, her son's and her nephew's. However, her son knew he was not up to the calibre of his cousin and remained envious. Albertine Agnes died, 24 May 1696, aged sixty-two.

Source: Leo van de Pas