Frederick William, elector of Hesse-Cas-sel, born Aug. 20, 1802. He succeeded to the electorate Nov. 20,1847. Although his mother was a daughter of king Frederick William II. of Prussia, he joined Austria in 1866, and as he declined to remain neutral in the war between that state and Prussia, or to accept the proposals of the latter for a reform of the German diet, a Prussian army under Gen. von Beyer invaded his territory (June 16), and he was arrested (June 23) and detained in the castle of Stettin. Despite the annexation of his electorate to Prussia with the consent of Austria, he would not relinquish his rights as a sovereign prince until Sept. 17, 1867, when he agreed to abdicate, on condition of receiving a life interest in the electoral crown domain, besides a sum of 600,000 thalers and the privilege of inhabiting the palaces in the province of Hanau. Since his release he has resided on his estates in Bohemia and in the palace of Prince Windischgratz, which he purchased, in Prague. In September, 1873, he renounced all his rights and personal property, on condition of Prussia's paying him an annuity of 200,000 thalers during his life.