Leaving 60,000 French to hold beaten Prussia, he now turned on Russia, and in February 1807 marched 100,000 men into Poland, where he met the Russian army and the remnants of the Prussian army. On a field covered with snow a battle was fought during the short hours of a winter day. The slaughter was horrible, and the battle was drawn. In the following May the armies met again, and this time Napoleon was victorious. A week later he and the Czar met on a raft moored on the river Niemen,[46] and made plans for the greatest scheme of robbery ever known to history: they agreed to divide Europe between them. Great Britain still struggled against Napoleon, and her fleet was the only force which prevented him from becoming the unchecked master of the whole world. Napoleon now tried to bring Great Britain to her knees. Some years before he had gathered fleets of flat-bottomed boats at Boulogne,[47] and had prepared a huge army for the invasion of Britain, but could not obtain that twelve hours' mastery of the Channel which would enable him to cross the "silver streak." Now he tried another plan. He ordered the harbours of the Continent to be closed against the British, so that they could not carry on trade or sell their manufactures. In this way he hoped to make Great Britain so poor that she would be unable to hold out against him. By this time the Czar was tired of being Napoleon's underling, and he now said that he would not close his ports against the British. Napoleon was furiously angry, and marched a great army towards the Russian frontier, which was crossed on June 23, 1812. The Russians did not attempt to fight; they fell back, and lured him on, meanwhile wasting the country over which he had to pass. Soon the French found themselves short of food, and thousands died of hunger. Napoleon's line of march was marked by the dead bodies of thousands of men and horses. At last the Russians stood firm, and a great battle was fought some seventy miles from Moscow. One hundred thousand men lay dead or wounded on the field, but Napoleon was not checked. A week later his troops entered Moscow[48] with shouts of delight. To their dismay they found it as silent as a city of the dead. All the people had left it, but before doing so had set fire to the place. Soon after the French marched in, flames began to shoot up from a thousand different points. The fire burned for five days, and the city lay in ruins. Then want of food and shelter compelled Napoleon to retreat. When he left Moscow his army had dwindled to about 100,000 men. The Cossacks[49] hung upon their flanks and rear, and cut off all stragglers. Soon the snow began to fall, and the cruel Russian winter set in. Thousands perished daily of cold and hunger.