To compensate for the loss of the Metternich's ancestral estates in the Moselle valley when the French Republic annexed the west bank of the Rhine, the Imperial Recess of 1803 brought Metternich's family new estates in Ochsenhausen, the title of Prince, and a seat in the Imperial Diet. In the ensuing diplomatic reshuffle Metternich was appointed ambassador to the Kingdom of Prussia, being notified of this in February 1803 and taking his position in November of that year. He arrived at a critical juncture in European diplomacy, soon growing worried about the territorial ambitions of Napoleon Bonaparte, newly the leader of France. This fear was shared by the Russian court under Alexander I, and the Tsar kept Metternich informed of Russian policy. By autumn of 1804 Vienna decided on action entered into in August 1805 when the Austrian Empire (as the Holy Roman Empire was in the process of becoming) began its involvement in the War of the Third Coalition. Metternich's now almost impossible task was to convince Prussia to join the coalition against Bonaparte. Their eventual agreement was not due to Metternich, however, and after the coalition's defeat at the Battle of Austerlitz, Prussia disregarded the agreement and signed a treaty with the French instead.