The fall of Warsaw meant the fall of Russian Poland, but Russia was not yet defeated. Von Hindenburg was to be treated as Napoleon was in 1812. The strategy of the Grand Duke was sound; so long as he could save the army the victories of Germany would be futile. It is true that the German armies were not compelled, like those of Napoleon, to live on the land. They could bring their supplies from Berlin day by day, but every mile they advanced into hostile territory made their task harder. The German line of communication, as it grew longer, became weaker, and the troops needed for garrison duty in the captured towns, seriously diminished the strength of the fighting army. The Russian retreat was good strategy and it was carried on with most extraordinary cleverness. It is unnecessary to describe the events which succeeded the fall of Warsaw in great detail. There was a constant succession of German victories and Russian defeats, but never was one of the Russian armies enveloped or destroyed. Back they went, day after day, always fighting; each great Russian fortress resisted until it saw itself in danger, and then safely withdrew its troops. Kovno fell and Novogeorgievsk, and Ivangorad, then Ossowietz was abandoned, and Brest-Litovsk and Grodno. On September 5th the Emperor of Russia signed the following order: Today I have taken supreme command of all the forces of the sea and land armies operating in the theater of war. With firm faith in the clemency of God, with unshakable assurance in final victory, we shall fulfil our sacred duty to defend our country to the last. We will not dishonor the Russian land. The Grand Duke Nicholas was made Viceroy of the Caucasus, a post which took him out of the main theater of fighting but gave him a great field for fresh military activity. He had been bearing a heavy burden, and had shown himself to be a great commander. He had outmaneuvered von Hindenburg again and again, and though finally the Russian armies under his command had been driven back, the retreat itself was a proof of his military ability, not only in its conception, but in the way in which it was done. The Emperor chose General Alexeiev as his Chief of General Staff. He was the ablest of the great generals who had been leading the Russian army. With this change in command a new spirit seemed to come over Russia. The German advance, however, was not yet completely checked. It was approaching Vilna.