In his will, Count Ernest left his domains to his only son Louis, under the regency of his mother Louise Juliane during his minority. In case he would die prematurely, his two surviving daughters would inherited the County. When Count Louis died four years later, the male line of Sayn-Wittgenstein-Sayn died out. A violent dispute over his inheritance erupted between the Dowager Countess and the three half-brothers of her late husband, who claimed the succession of the whole County. After two months, one of them, Count Louis Albert of Sayn-Wittgenstein-Neumagen, finally forced Louise Juliane to surrender the County to him and his brothers. In the meanwhile, Count Christian, Louis Albert's youngest brother besieged Altenkirchen and the Electorate of Mainz besieged Hachenburg, who was forced to surrender when the food ran out; without options, Louise Juliane and her daughters fled to Freusburg. When the Electorate of Trier prepared to besiege Freusburg, they fled to Friedewald, where they found safety. Louise Juliane sued her in-laws before the Reichskammergericht and the Emperor. She sent her councillors to Münster and Osnabrück where the Peace of Westphalia of 1648 was being negotiated. The rights of Johannetta and Ernestine were recognized and, with Swedish assistance, one part of the county after the other was returned to her. During her family exile in Friedewald, Johannetta married on 30 September 1647 to Landgrave John of Hesse-Braubach, younger brother of George II, Landgrave of Hesse-Darmstadt; however, Louise Juliane retained the regency of the County of Sayn-Wittgenstein-Sayn for her two daughters. After four years of childless union, Landgrave John died on 1 April 1651 in Bad Ems.
Rule
One year later, Louise Juliane finally handed over the County of Sayn to her daughters, who was divided in two parts: Sayn-Wittgenstein-Sayn-Altenkirchen and Sayn-Wittgenstein-Sayn-Hachenburg. In Wallau on 29 May 1661, Johannetta married secondly to Prince John George, third surviving son of William, Duke of Saxe-Weimar. After the death of Duke William, his two older sons inherited almost all the family domains; as result, John George only received an income from the new duchy of Saxe-Eisenach and the small town of Marksuhl as residence. For this, Johannetta and her husband mainly resided in her County, where all her children were born. The successive death of Dukes Adolf William and William August of Saxe-Eisenach, enabled John George to inherited this part of the paternal domains. Since them, Johannetta became Duchess consort of Saxe-Eisenach. Johannetta died in Jena aged 69, having survived her second husband and six of her children. She was buried in the Georgenkirche, Eisenach. The County of Sayn-Wittgenstein-Sayn-Altenkirchen remained united to the Duchy of Saxe-Eisenach until 1741, when Johannetta's male line died out. Then, the County was inherited by Charles William Frederick, Margrave of Brandenburg-Ansbach, grandson of Eleonore Erdmuthe, Johannetta's eldest daughter. In 1803, the County was mediatised to Nassau-Weilburg.
