Rantzau went to France, and served under Maréchal de Löwendal; but, one fine day, he left his regiment in order to attach himself to the car of an Italian singing woman. During his amorous odyssey, he passed through all sorts of adventures, and assumed all sorts of shapes, like a veritable Proteus. At one time, he appeared with all the splendour becoming his birth and condition; at another, he lived at Rome in a monk's gown. For some time, he remained _incognito_ with a troupe of comedians. During this career he often ran short of money, and at times procured it how he could. He was tried criminally in Sicily for swindling; and, at Naples, the French envoy had to hush up an ugly matter in consideration of his family. At Genoa, he impudently drew a bill on his father, "the Viceroy of Norway," though his father was only a plain country gentleman, and had turned him up long before. In 1761, on the death of Elizabeth, when a war was anticipated between Russia and Denmark, Rantzau had the impudence to offer his services to Peter III. as a Holstein gentleman who had a right to serve his duke. His offer was spurned, and Rantzau swore revenge. He wormed himself into the confidence of the Empress Catharine and Count Orloff; and was mixed up in the conspiracy against Peter III. As he was coldly treated, and passed over instead of being rewarded when Catharine ascended the throne, he returned to Holstein very angry, and brooding over revenge. It was at this period that his fatal connection with Struensee commenced, as we have seen. Soon after the death of Frederick V., Rantzau acquired the favour of Count St. Germain, who was omnipotent at court; and the latter procured him the rank of Lieutenant-General in 1766, and, in the following year, the chief command of the Norwegian army. He behaved in a very reckless manner, and was suddenly dismissed from active service in 1768, after Bernstorff and Saldern had succeeded in removing St. Germain from his post as generalissimo of the army and head of the War Office.[112] After this, Rantzau returned to Holstein, where he inherited the family estates, on the death of his father, in 1769.