The campaign of 1813 falls naturally into three parts. During the first, from the beginning of January to the latter part of April the victorious Russians swept over North Germany, and, carrying the Prussian monarchy with them, strengthened a reaction which had already begun against the rule of Napoleon. The second part began with the arrival of Napoleon on the scene of action towards the end of April and lasted to the conclusion of an armistice on June 4. In this period of seven or eight weeks the allies were forced to retire at all points and the war was carried into Prussian territory. The armistice, which terminated on August 10, preceded the opening of the third part of the campaign in which Russia and Prussia were joined by Austria and Sweden, and, after gradually drawing closer round the main French position in Saxony, finally inflicted a crushing defeat upon Napoleon at Leipzig in the middle of October. The campaign was virtually over when Napoleon secured his retreat by the victory of Hanau on October 30; but it is impossible to sever it from the events outside Germany which were directly occasioned by the downfall of Napoleon's German domination. These are the revolt of Holland in November, that of Switzerland in December, and the Austrian attack on Northern Italy in October and November. In the opening months of the campaign the movements were merely a sequel to those of the previous year. The French retreat was continued from the Niemen to the Vistula, the Elbe, and finally the Saale. The Russians entered Prussia proper a few days after Yorck's capitulation, and the French retired before them. Stein, the Prussian statesman who had received a commission from Russia to administer the Prussian districts occupied by her, ordered the provincial governor to convoke an assembly. Although some indignation was felt at such a step being taken by Russian orders, the assembly met and voted the formation of the Landwehr. In this way Prussia actually began to arm against France, while the Prussian government still professed to maintain the French alliance. A few days later King Frederick William left Berlin, which was still occupied by the French, for Breslau. Before the end of February he had concluded the treaty of Kalisch with Russia, by which the two powers were to conduct the war against France conjointly, and Russia was not to lay down her arms till Prussia should be restored to a strength equal to that which she had possessed in 1806. On March 2 Cathcart arrived at Kalisch as British ambassador to the Russian court. He actively promoted Russia's alliance with Prussia, from which Great Britain stood apart for the present. He was able to obtain from Prussia a renunciation of her claims on Hanover, but Frederick William was still opposed to any increase of Hanoverian territory. On the 17th Prussia declared war on France. By that time the Russians had entered both Berlin and Breslau,