At the conference of ministers which met at Vienna, on the 20th of November, for the purpose of "developing and completing the Federal Act of the congress of Vienna," Metternich found himself face to face with a more formidable opposition than at Carlsbad. The "middle" states, headed by Württemberg, had drawn together, to form the nucleus of an inner league of "pure German States" against Austria and Prussia, and of "Liberal particularism" against the encroachments of the diet. With Russia and, to a certain extent, Great Britain sympathetic, it was impossible to ignore their opposition. Moreover, Prussia was hardly prepared to endorse a policy of greatly strengthening the authority of the diet, which might have been fatal to the Customs Union of which she was laying the foundation. Metternich realized the situation, and yielded so gracefully that he gave his temporary defeat the air of a victory. The result was that the Vienna Final Act (May 15,1820), which received the sanction of the diet on the 8th of June, was not unsatisfactory to the lesser states while doing nothing to lessen Austrian prestige. This instrument merely defined more clearly the principles of the Federal Act of 1815. So far from enlarging the powers of the diet, it reaffirmed the doctrine of non-intervention; and, above all, it renewed the clause forbidding any fundamental modification of the constitution without a unanimous vote. On the vexed question of the interpretation of Article 13 Metternich recognized the inexpediency of requiring the South German states to revise their constitutions in a reactionary sense. By Articles 56 and 57, however, it was laid down that constitutions could only be altered by constitutional means; that the complete authority of the state must remain united in its head; and that the sovereign could be bound to co-operate with the estates only in the exercise of particular rights. These provisions, in fact, secured for Metternich all that was necessary for the success of his policy: the maintenance of the _status quo_. So long as the repressive machinery instituted by the Carlsbad Decrees worked smoothly, Germany was not likely to be troubled by revolutions. Revolutions of 1830.