Charles Augustus, grand duke of Saxe-Weimar-Eisenach, born Sept. 3, 1757, died June 14, 1828. Having lost his father in the first year of his life, he was very carefully educated together with his posthumous brother, Frederick Ferdinand Constantine, under the regency of his young mother, who in the first year after the death of her husband was herself still under the guardianship of her father. Upon the recommendation of Frederick the Great she appointed as their governor the count of Gortz, afterward Prussian minister, giving them as teachers Seid-ler and Hermann, Wieland and Knebel, while Schmid conducted the affairs of the little state through the difficulties of the seven years' war. In December, 1774, Charles Augustus together with his brother entered upon a journey to France and Switzerland, during which he made the acquaintance of Goethe, who became his friend, and afterward his minister. Having been declared reigning duke by his mother on his 18th birthday, he married Louisa, princess of Hesse-Darmstadt, and continued the liberal and reformatory government of his mother, gathering around him at Weimar a circle of distinguished men, among whom were Goethe, Herder, Wieland, and Schiller. In 1786 he took service in the Prussian army, was in the campaigns of 1792-3 on the Rhine as volunteer, was made Prussian lieutenant general in 1797, and remained in service till after the battle of Jena (1806), when he retired to his dukedom and joined the Rhenish confederacy.

His soldiers now fought for Napoleon in Tyrol, Spain, and Russia. Having gone over to the coalition in 1813, he entered the Russian service in the following year, and led an army of Saxons, Hessians, and Russians into the Netherlands. He then went to Paris, London, and Vienna, and took part in the campaign of 1815. The congress of Vienna rewarded him by enlargiug his state, and erecting it into a grand duchy, besides granting him a compensation of 800,000 thalers. He was the first of the German princes to introduce the promised constitutional representation (1816), and allowed freedom to the press, until he was induced to adopt restrictive measures by the complications that followed the great gathering at the Wartburg in 1817. He died of apoplexy at Graditz, near Torgau, on his return from Berlin. Several scientific and agricultural institutions, a park, and a botanical garden are among the improvements with which he adorned his country.