On that same day (July 7th) the Treaty of Tilsit was signed. Its terms may be thus summarized. Out of regard for the Emperor of Russia, Napoleon consented to restore to the King of Prussia the province of Silesia, and the old Prussian lands between the Elbe and Niemen. But the Polish lands seized by Prussia in the second and third partitions were (with the exception of the Bialystock district, now gained by Russia) to form a new State called the Duchy of Warsaw. Of this duchy the King of Saxony was constituted ruler. Danzig, once a Polish city, was now declared a free city under the protection of the Kings of Prussia and Saxony, but the retention there of a French garrison until the peace made it practically a French fortress. Saxe-Coburg, Oldenburg, and Mecklenburg-Schwerin were restored to their dukes, but the two last were to be held by French troops until England made peace with France. With this aim in view, Napoleon accepted Alexander's mediation for the conclusion of a treaty of peace with England, provided that she accepted that mediation within one month of the ratification of the present treaty. On his side, the Czar now recognized the recent changes in Naples, Holland, and Germany; among the last of these was the creation of the Kingdom of Westphalia for Jerome Bonaparte out of the Prussian lands west of the Elbe, the Duchy of Brunswick, and the Electorate of Hesse-Cassel. Holland gained East Frisia at the expense of Prussia. As regards Turkey, the Czar pledged himself to cease hostilities at once, to accept the mediation of Napoleon in the present dispute, and to withdraw Russian troops from the Danubian Provinces as soon as peace was concluded with the Sublime Porte. Finally, the two Emperors mutually guaranteed the integrity of their possessions and placed their ceremonial and diplomatic relations on a footing of complete equality. Such were the published articles of the Treaty of Tilsit. Even if this had been all, the European system would have sustained the severest blow since the Thirty Years' War. The Prussian monarchy was suddenly bereft of half its population, and now figured on the map as a disjointed land, scarcely larger than the possessions of the King of Saxony, and less defensible than Jerome Bonaparte's Kingdom of Westphalia; while the Confederation of the Rhine, soon to be aggrandized by the accession of Mecklenburg and Oldenburg, seemed to doom the House of Hohenzollern to lasting insignificance.[153]