Frederick was born in Kassel. As the eighth child of Landgrave Maurice of Hesse-Kassel, he was awarded Hesse-Eschwege by a decree of his father, which was imposed on his father by his eldest brother William V shortly before Maurice had to abdicate to avoid an impending bankruptcy. At the instigation of his second wife, Juliane of Nassau-Dillenburg, Maurice set aside a quarter of his country, the so-called Rotenburg Quarter, to be divided among his married sons. Of those, Herman IV received the Rotenburg area, Frederick received Eschwege and Ernest received the former Lower County of Katzenelnbogen, around Rheinfels Castle.
Life
Maurice himself lived with his second family in Eschwege until his death in 1632. His widow then moved to Rotenburg Castle with her children. The castle and town of Eschwege were pillaged and looted during the Thirty Years' War at Easter 1637. Thus, 20-year-old Frederick likely only moved into his residence at Eschwege after his marriage in 1646 in Stockholm with Eleonora Catherine, the sister of King Charles X Gustav of Sweden. Frederick had a successful military career in the Swedish army, where he made it to the Major General. It is unknown whether he was active during the Thirty Years' War. During the Second Northern War, he commanded a Swedish battle group. Due to his military career, he spent much time at the Swedish court and rarely visited Eschwege. His three brothers ruled his share of the Rotenburg Quarter on his behalf. Even so, he cared about his subjects and contributed significantly to the reconstruction after the end of the Thirty Years' War. His wife mostly stayed in Eschwege and his children were born there.
Death and legacy
Frederick died on 24 September 1655 in Costian near Poznań, Poland, during the Second Northern War, in the army of his brother-in-law Charles XGustav of Sweden. He was buried in the MarketChurch in Eschwege; it took two years before his coffin arrived there. Hesse-Eschwege fell to his brother Ernest of Hesse-Rheinfels. The castle in Eschwege was assigned to his widow as dower, but she retreated to her Swedish fief Osterholz near Bremen. She died in 1692 and was buried in the royal crypt in the Market Church in Eschwege. The castle in Eschwege was mortgaged to Brunswick-Bevern in 1667, to raise a dowry for his daughter Christina.
