Köthen until 1723, where he worked with violinist Christian Ferdinand Abel and met with singer Anna Magdalena Wilcke, who became his second wife in 1721. Prince Leopold died in 1728 at the age of 33; as he left no sons, his principality fell to his brother Augustus Louis. Upon his death in 1755, Prince Augustus Louis was succeeded by his second-born son Karl George Leberecht. During the Seven Years' War, Karl George tried to ease the impact on his principality; in 1751 he joined the Prussian Army and became a general in the Habsburg Imperial Army in 1789; soon after he was killed in the Siege of Belgrade. He was succeeded by his son Augustus Christian, who received parts of the extinct Principality of Anhalt-Zerbst in 1793 and was elevated to a duke (Herzog) by Napoleon in 1806. Anhalt-Köthen became a member of the German Confederation of the Rhine in 1807. Prince Augustus Christian died in 1812, and the ducal title passed to his minor nephew Louis Augustus Karl Frederick Emil, son of Prince Louis, himself the younger brother of Prince Augustus Louis. Duke Leopold III of Anhalt-Dessau acted as regent, however, Louis Augustus died in 1818 at the age of 16, leaving no heirs. Anhalt-Köthen-Pless In 1765, Frederick Erdmann, the youngest son of Prince Augustus Louis, had received the Silesian state country in the former Duchy of Pless from the hands of his maternal uncle, Count John Erdmann of Promnitz. From that time on, he styled himself as Prince of Anhalt-Köthen-Pless. His son, Frederick Ferdinand, inherited the princely title in 1797. Upon the early death in 1818 of Louis Augustus, Duke of Anhalt-Köthen, Frederick Ferdinand inherited the ducal title of Anhalt-Köthen. He then ceded Pless to his younger brother, Henry. Upon Frederick Ferdinand's death in 1830, Henry succeeded him as Duke of Anhalt-Köthen. He left Pless to the youngest brother, Louis, who predeceased him in 1841. With Henry's death in 1847, the Anhalt-Köthen line became extinct, and all territories passed to Duke Leopold IV of Anhalt-Dessau. Princes of Anhalt-Köthen (1396–1562) Albert IV 1396–1423 Adolph I 1423–1473 Waldemar V 1423–1436 (co-regent) Waldemar VI 1471–1508 (Anhalt-Dessau line) Albert VI 1473–1475 Philip 1475–1500 Magnus 1475–1508 (co-regent, son of Adolph I) (d. 1524) Adolph II 1475–1508 (co-regent, son of Adolph I) (d. 1526) Wolfgang 1508–1562 (d. 1566) To Prince Joachim Ernest of Anhalt-Zerbst. Princes of Anhalt-Köthen (1603–1806) Louis 1603–1650 Augustus of Anhalt-Plötzkau regent