The naming of the city of Constantinople, which is in Roumelia, betokens a superfluity of prudence. But it helps to confirm the statement of Napoleon's secretary, M. Méneval, that the future of that city led to a decided difference of opinion between the Emperors. After one of their discussions, Napoleon stayed poring over a map, and finally exclaimed, "Constantinople! Never! It is the empire of the world." Doubtless it was on this subject that Alexander cherished some secret annoyance. Certain it is that, despite all his professions of devotion to Napoleon, he went back to St. Petersburg ill at ease and possessed with a certain awe of the conqueror. For what had he gained? He received a small slice of Prussian Poland, and the prospect of aggrandizement on the side of Turkey and Sweden, Finland being pointed out as an easy prey. For these future gains he was to close his ports to England and see his commerce, his navy, and his seaboard suffer. It is not surprising that before leaving Tilsit he remarked to Frederick William that "the most onerous condition imposed by Napoleon was common to Russia and Prussia."[155] This refers to the compulsion put upon them to join Napoleon's Continental System. In the treaty signed with Prussia on July 9th, Napoleon not only wrested away half her lands, but required the immediate closing of all her ports to British vessels. We may also note here that, by the extraordinary negligence of the Prussian negotiator, Marshal Kalckreuth, the subsequent convention as to the evacuation of Prussia by the French troops left open a loophole for its indefinite occupation. Each province or district was to be evacuated when the French requisitions had been satisfied.[156] The exaction of impossible sums would therefore enable the conquerors, quite legally, to keep their locust swarms in that miserable land. And that was the policy pursued for sixteen months. Why this refinement of cruelty to his former ally? Why not have annexed Prussia outright? Probably there were two reasons against annexation: first, that his army could live on her in a way that would not be possible with his own subjects or allies; second, that the army of occupation would serve as a guarantee both for Russia's good faith and for the absolute exclusion of British goods from Prussia.[157] This had long been his aim. He now attained it, but only by war that bequeathed a legacy of war, and a peace that was no peace. Napoleon's behaviour at Tilsit has generally been regarded, at least in England, as prompted by an insane lust of power; and the treaty has been judged as if its aim was the domination of the Continent. But another explanation, though less sweeping and attractive, seems more consonant with the facts of the case.