Frederick Augustus I., first king of Saxony, eldest son of the elector Frederick Christian, born Dec. 23, 1750, died May 5, 1827. He succeeded his father in December, 1763, under the tutelage of Prince Xavier, was declared of age Sept. 15, 1768, and in the following year married Maria Amalia, princess of Zweibrucken. The only fruit of this marriage was a daughter, the princess Augusta. He abolished the heavy taxes on foreign merchandise, consolidated the several departments for the management of the finances, encouraged industry, and improved navigation with canals and sluices. Paper money soon rose above par. He abolished torture and the farming of judicial offices, and reorganized the court of appeals. The claims of his mother to the possessions of her deceased brother, the elector Maximilian Joseph of Bavaria, induced him to ally himself with Frederick the Great against Austria in the short war of the Bavarian succession. Subsequently he joined the league of princes (Furstenbund) formed nnder the protectorate of the Prussian monarch.

In 1791 he declined the succession to the throne of Poland, offered him in the name of that country by Prince Adam Casimir Czartoryski. He also rejected the overtures of a conference of the emperors Leopold II. and Frederick William II. of Prussia, held at Pilnitz (1791), to join as an independent sovereign the first coalition against the French revolution, though he did not withhold his contingent as a member of the German empire when the war had been declared. In 1796 he took part in the treaty of peace and neutrality concluded with the French republic by the district of Upper Saxony. He maintained his neutrality during the war of 1805, but in the following year joined Prussia in the unhappy contest decided by the battle of Jena. Saxony, which fell into the hands of the French conqueror, was severely punished, and Frederick Augustus was compelled to ally himself with Napoleon. He assumed the title of king, and joined the Rhenish confederation. For the cession of several districts of western Saxony annexed to the new kingdom of Westphalia he was scantily compensated by a part of Lusatia, and after the peace of Tilsit (1807) more liberally by the duchy of Warsaw. He was a faithful vassal of the French emperor during the wars of 1809 against Austria and 1812 against Russia, and in 1813, when Saxony became the chief scene of the conflict.

Having personally joined Napoleon shortly before the battle of Leipsic, he was declared after its bloody issue a prisoner of war by the emperor Alexander, was sent to Berlin, and afterward to the castle of Fried-richsfeld, but was allowed to reside at Presburg during the deliberations of the congress of Vienna. That congress restored to him half of his German possessions, the other half being annexed to Prussia; the duchy of Warsaw was made a dependence of Russia as the kingdom of Poland. Returning to his capital in June, 1815, Frederick Augustus spent the last 12 years of his life in healing the wounds of his diminished country by promoting its agricultural, commercial, and mining interests, by establishing or developing institutions of art and science, and particularly by a strict administration of justice. His subjects bestowed upon him the surname of the Just. His brother Anthony succeeded him.