Much that is highly conjectural has been written about the plans of campaign of the two Emperors. That of Napoleon may be briefly stated: it was to find out the enemy's chief forces, divide them, or cut them from their communications, and beat them in detail. In other words, he never started with any set plan of campaign, other than the destruction of the chief opposing force. But, in the present instance, it may be questioned whether he had not sought by his exasperating provocations to drive Prussia into alliance with the Czar. In that case, Alexander would have been bound in honour to come to the aid of his ally. And if the Russians ventured across the Niemen, or the Vistula, as Napoleon at first believed they would,[256] his task would doubtless have been as easy as it proved at Friedland. Many Prussian officers, so Müffling asserts, believed that this was the aim of French diplomacy in the early autumn of 1811, and that the best reply was an unconditional surrender. On the other hand, there is the fact that St. Marsan, Napoleon's ambassador at Berlin, assured that Government, on October 29th, that his master did not wish to destroy Prussia, but laid much stress on the supplies which she could furnish him--a support that would enable the Grand Army to advance on the Niemen _like a rushing stream_. The metaphor was strangely imprudent. It almost invited Prussia to open wide her sluices and let the flood foam away on to the sandy wastes of Lithuania; and we may fancy that the more discerning minds at Berlin now saw the advantage of a policy which would entice the French into the wastes of Muscovy. It is strange that Napoleon's Syrian adage, "Never make war against a desert," did not now recur to his mind. But he gradually steeled himself to the conviction that war with Alexander was inevitable, and that the help of Austria and Prussia would enable him to beat back the Muscovite hordes into their eastern steppes. For a time he had unquestionably thought of destroying Prussia before he attacked the Czar; but he finally decided to postpone her fate until he had used her for the overthrow of Russia.[257] After the experiences of Austerlitz and Friedland, the advantages of a defensive campaign could not escape the notice of the Czar. As early as October, 1811, when Scharnhorst was at St. Petersburg, he discussed these questions with him; and not all that officer's pleading for the cause of Prussian independence induced Alexander to offer armed help unless the French committed a wanton aggression on Königsberg. Seeing that there was no hope of bringing the Russians far to the west, Scharnhorst seems finally to have counselled a Fabian strategy for the ensuing war; and, when at Vienna, he drew up a memoir in this sense for the guidance of the Czar.[258]