Talleyrand was a long-serving French diplomat under the regimes of Louis XVI, Napoleon I, Louis XVIII, Charles X and Louis-Philippe. Unable to embark on a military career due to a congenital disorder affecting his leg, he was directed towards religion and ordained as a priest in 1779. He rose to Bishop of of Autun in 1801 but later resigned. He spent time in England and the United States before returning to Paris in 1796 when he formed an alliance with Napoleon Bonaparte. During the French Empire he was appointed Grand Chamberlain of the Empire and later Minister of Foreign Affairs, a post from which he resigned in 1807 in exchange for the role of Vice Grand Elector. He was involved in the negotiations between Emperor Napoleon and Tsar Alexander I of Russia regarding an anti-Austrian military alliance but the outcome of the talks displeased Napoleon and Talleyrand began to distance himself from the emperor, whom he believed could not sustain his rule. Talleyrand was a key figure in the Restoration and was the chief negotiator at the Congress of Vienna. After the return of Napoleon in 1815 during the Hundred Days, he became a less promienent figure at court and under the rule of King Louis-Philippe he served as ambassador to the United Kingdom.