It was apparent to all that this condition of tension must come to an end; and, though there was no certainty that the King could maintain himself on the throne without foreign support, yet it was evident that the cure for the evils to be dreaded, was liable to become a greater misfortune to Europe, than the apprehension itself. The French, moreover, had made great efforts to discharge their financial obligations to the Allies; and in these efforts they were successful, aided by the Duke of Wellington, who, upon the proposal of the Emperor of Russia, was appointed president of the diplomatic and finance committee charged with the regulation of these liabilities.[118] Added to this, the fortifications of the Netherlands frontier were by this time nearly completed, and as this was done to form a barrier against France, the moment had arrived when the country could be delivered from the burden that oppressed it, as well as from the cause which produced so much irritation. ----- Footnote 118: Sir Archibald Alison, _History of Europe from the Fall of Napoleon in 1815, to the Accession of Louis Napoleon in 1852_ , i. 538 (London, 1852). _Supplementary Despatches, etc._ , xii. 119, 156, 193. ----- In the autumn, therefore, of 1818, a Congress was convened at Aix-la-Chapelle, for the purpose of determining the question;[119] and an agreement was made, on the 1st of October, by which the foreign forces were to leave the soil of France on or before the 30th of November. To this compact was added an invitation to His Most Christian Majesty to join the four Great European Powers, and to take part in their deliberations, present or future, for the maintenance of peace, and for the mutual guarantee of the rights of nations. The conference, however, did not end there; for a secret convention was also signed, by the four Powers only, stipulating that, in case France should resume her revolutionary ways, and again threaten the tranquillity of the civilized world, British, Prussian, Austrian, and Russian _corps d’armées_ were to assemble forthwith at Brussels, Cologne, Stuttgart, and Mainz respectively, for the suppression of these disorders.[120] ----- Footnote 119: M. de Richelieu, present on the part of France, was instructed only to obtain the emancipation of France. “Make every sacrifice,” said the King to him at his departure, “to obtain the evacuation of the territory. It is the first condition of our independence. No flag but our own should wave in France. Express to my Allies how difficult my government will be so long as it can be reproached with the calamities of the country, and the occupation of the territory.... Obtain the best conditions possible; but at any sacrifice, get quit of the stranger” (Alison, _History of Europe, 1815-1852_ , i. 566). Footnote 120: _Ibid._ , i. 568, etc. -----