He studied at the
University of Giessen and was sent by his father to Russia in 1723. He became Major-General in Riga and commander of the Narva Regiment. As the grandson of Princess
Louise Elisabeth of Courland, he hoped in vain to succeed his cousin
Ferdinand Kettler as
Duke of Courland.
Anna of Russia moved him to Saint Petersburg, where he was promoted to General-Lieutenant and commander of the Saint Petersburg garrison. In 1732, he led a successful campaign against the
Crimean Tatars in the Caucasus. After operations in Eastern Poland
in 1734–1735, he again fought against the Crimean Tatars and the Turks
in 1736–1737, but now under command of Count
Burkhard Christoph von Münnich. He was awarded with the rank of General-Feldzeugmeister and was appointed Governor of Astrakhan and the Persian provinces. Ludwig Gruno also had good relations with the new Empress
Elizabeth of Russia. She gave him in 1742 the title of General-Fieldmarshal, a house in Moscow and an estate in Livonia. He died from illness on a travel in Berlin. He pre-deceased his father and was buried in the crypt of
Bad Homburg Castle. == Family ==