His journal, an invaluable clue to the complicated intrigues of this period, was published in 1891 in French and German, under the title of "Une Année de ma vie, 1848–1849". In March 1849 he was sent on a special mission to Paris, and later in the same year was appointed ambassador to France. His influence was in large measure due to the friendly attitude of Austria to the Allies in the Crimean War, at the close of which he represented Austria at the Congress of Paris (1856). He allowed himself, however, to be taken by surprise by Napoleon's intervention on behalf of Italian unity, of which the first public intimation was given by the French emperor's cold reception of Hübner on New Year's Day, 1859, with the famous words, "I regret that our relations with your Government are not so good as they have hitherto been."