In 1758 he was declared of age and assumed the government of his lands. An
Anglophile and strong supporter of the
Enlightenment, Leopold took special interest in the education of the population of his principality in science and nature. His numerous reforms in the areas of education, health care, social services, roads, agriculture, forestry, and industry made Anhalt-Dessau one of the most modern and prosperous of the small German states. The most conspicuous of his improvements included planting fruit trees along dykes and the construction of beautiful buildings. However his reforms included public works programs repairing dykes destroyed by flooding, providing social housing, education, sanitation, the first public parks, burial grounds irrespective of social rank, as well as liberal policies towards the Jewish community, including allowing for the founding of a Jewish school and the first Jewish newspaper in Germany. He engaged
Friedrich Wilhelm von Erdmannsdorff to build
Wörlitz Palace (1769–1773), the first
Neoclassical building in Germany. In 1774 Leopold engaged von Erdmannsdorff to construct a small residence with a small English park as a gift to his wife; in her honor, the castle took the name
Schloss Luisium. Leopold also extended and altered the old gardens of
Oranienbaum that were laid out in Dutch style to create the first and largest of the
English parks of his time, renamed the Dessau-Wörlitz Garden Realm. In 1782, Leopold was tried by the
Fürstenbund for his opposition to Prussian hegemony. In 1806 he was invited to Paris by
Napoleon, who was impressed by his reputation. Leopold was one of the last princes to join the
Confederation of the Rhine on 18 April 1807. On the other hand, despite his differences with the Prussian crown, he offered the Prussian rebel Major
Ferdinand von Schill an honorable reception in Dessau on May 2, 1809. Leopold was elevated to the rank of duke in 1807. As the head of the senior Anhalt branch, he could not earlier by etiquette receive his kinsmen, the Princes of
Anhalt-Köthen and
Anhalt-Bernburg, who were raised to that rank before him. He received the title by paying a considerable sum of money to the Emperor shortly before the dissolution of the
Holy Roman Empire in 1806, just as the prince of Anhalt-Bernburg had done before him. In 1812, Leopold became regent of the duchy of Anhalt-Köthen during the minority of
Duke Louis Augustus Karl Frederick Emil. Leopold died after a fall from his horse at
Schloss Luisium, near Dessau, in 1817. He was succeeded by his eldest grandson
Leopold IV, because his son, the
Hereditary Prince Frederick, had predeceased him. ==Marriage and issue==