On May 1 Lord Ponsonby, the newly appointed British ambassador, arrived at Constantinople, preceding by three days Count Orloff, the _generalissimo_ of the Russian military and naval forces in the Black Sea and the Bosphorus, and Ambassador-Extraordinary to the Sublime Porte. His appointment was due to the Tsar's desire to be represented at Constantinople by some one who could be depended upon resolutely to oppose Admiral Roussin. Boutenieff appears to have been considered as somewhat deficient both in energy and strength of character. Orloff had been furnished with very wide powers, but he was charged to regard the task of convincing the Sultan and his ministers that their safety entirely depended upon the degree of support which, in the future, the Tsar might be disposed to afford them, as the primary object of his mission. He must be admitted to have carried out his instructions most faithfully. From the day of his arrival Russian influence was supreme at the Porte and in the Divan. Roussin's request that French war ships should be allowed to pass through the Dardanelles was peremptorily refused. Ponsonby saw clearly that, for the time being, he must submit to be overshadowed completely by the Russian ambassador. For the present he could only gaze moodily from his windows at the Russian encampment in the valley of Unkiar-Skelessi and endeavour to restrain his French colleague from affording Orloff any excuse for delaying the departure of his troops. At last, on July 9 and 10, the Egyptian withdrawal behind the Taurus mountains having been completely carried out, the Tsar's soldiers were embarked and his ships sailed out of the Bosphorus.[308] For some weeks prior to the departure of the Russian expedition, it had been reported that an offensive and defensive treaty was on the point of being concluded between the Tsar and the Sultan.[309] The truth of this rumour was confirmed after Orloff had quitted Constantinople. It would appear that it was the Sultan himself who first suggested an alliance, at an audience accorded to Orloff shortly after his arrival, and that Ahmed Pasha acted as the intermediary between the palace and the Russian embassy in the very secret negotiations which followed. The diplomatic instrument, known as the Treaty of Unkiar-Skelessi, concluded between the Porte and Russia on July 8, 1833, for a duration of eight years, consisted of six public and one secret article. The public articles merely proclaimed the existence of peace and friendship between the two Empires and provided for their mutual succour in case of need. The whole importance of the treaty lay in the secret clause in which it was stipulated that, inasmuch as Russia had no intention of exercising her right to ask for military assistance, the Porte, in return, would, "upon demand and in accordance with the principle of reciprocity,"[310] close the Dardanelles to the warships of all nations.