Being without a patrimony, he was educated at court as page in the house of Frederick V. As he evidenced talent and cunning, Count von Moltke granted him a pension to study abroad. During his first journey to Leipzig, he made the acquaintance of Count Stanislaus Poniatowski, afterwards King of Poland, and they even slept in the same bed. On returning home, the first use Osten made of his talents was to induce the page of the chamber to deliver to the king a memorial against Count von Moltke and his administration, and against Bernstorff, who had the confidence of the king and his favourite. The king, instead of dismissing his favourite and his minister, showed them the libel, and as they soon saw that the person who handed it in was not capable of composing it, they urged him to reveal the real author. Moderate and honourable as they were, they took no further vengeance than sending their young adversary to take some lessons in politics, and for this purpose entrusted him to Malzahn, at that time minister in Russia. Although Von der Osten was not given an official post, he contrived to seize on one. Malzahn died, and the secretary to the embassy being ill, Osten took upon himself to seal up the archives, receive despatches, and confer with the Russian ministers. Bernstorff confirmed him in the appointment he had seized, and sent him his instructions, which were, among other things, that he must humour the grand duchess, whose elevation the Copenhagen cabinet already foresaw. Von der Osten paid his court to her, by telling her all he could learn about foreign politics. This young princess was silently preparing to play a part, though I cannot affirm whether she flattered herself with the hope of managing her husband, or that she thought even then of getting rid of him.