At last, on June 24, Napoleon's grand army began the passage of the Niemen, which formed the boundary between the duchy of Warsaw and the Russian empire. The main body, at least 300,000 strong, was commanded by Napoleon himself. A northern division, including the Prussian contingent, was commanded by Macdonald, and, after advancing to Riga, which it pretended to besiege, remained idle throughout the campaign. The Austrians, under Schwarzenberg, formed a southern division, but they merely manoeuvred, and made no serious attempts to impede the movements of the southern Russian army on its return journey from the war on the Danube. Napoleon himself drove the main Russian armies before him in the direction of Moscow. At last Kutuzov, who had taken over the command of the Russians in the course of the retreat, made a stand at Borodino, where on September 7 one of the bloodiest battles on record was fought. The figures are variously given, but the French army probably lost over 30,000 in killed and wounded out of a force of 125,000; and the Russians lost not less than 40,000 out of an army of slightly smaller dimensions. This awful carnage ended, after all, in little more than a trial of strength. The French gained the ground, but the Russians made good their retreat, and six days later Kutuzov retired through the streets of Moscow, taking the better part of the population and all the military stores with him. The French vanguard entered on the 14th, and Napoleon himself next day. A fire, kindled either by accident or by Russian incendiaries, raged from the 14th to the 20th and destroyed three-fourths of the city. [Pageheading: _NAPOLEON'S RETREAT FROM MOSCOW._]