It was a piece of great audacity in the Emperor to entrust his left wing, as well as his right and his retreat, to Prussians and Austrians.  It was observed, that at the same time he had dispersed the Poles throughout the whole army; many persons thought that it would have been preferable to collect in one point the zeal of the latter, and to have divided the hatred of the former.  But we everywhere required natives as interpreters, scouts, or guides, and felt the value of their audacious ardour on the true points of attack.  As to the Prussians and Austrians, it is probable that they would not have allowed themselves to be dispersed.  On the left, Macdonald, with seven thousand Bavarians, Westphalians, and Poles, mixed with twenty-two thousand Prussians, appeared sufficient to answer for the latter, as well as for the Russians.

In the advance march, there had been at first nothing to do, but to drive the Russian posts before them, and to carry off some magazines.  Afterwards there were a few skirmishes between the Aa and Riga.  The Prussians, after a rather warm affair, took Eckau from the Russian General Lewis; after which both sides remained quiet for twenty days.  Macdonald employed that time in taking possession of Duenaburg, and in getting the heavy artillery brought to Mittau, which was necessary for the siege of Riga.

On the intelligence of his approach, on the 23d of August, the commander-in-chief at Riga made all his troops march out of the place in three columns.  The two weakest were to make two false attacks; the first by proceeding along the coast of the Baltic sea, and the second directly on Mittau; the third, which was the strongest, and commanded by Lewis, was at the same time to retake Eckau, drive back the Prussians as far as the Aa, cross that river, and either capture or destroy the park of artillery.

The plan succeeded as far as beyond the Aa, when Grawert, supported latterly by Kleist, repulsed Lewis, and following the Russians closely as far as Eckau, defeated them there entirely, Lewis fled in disorder as far as the Duena, which he recrossed by fording it, leaving behind a great number of prisoners.

Thus far Macdonald was satisfied.  It is even said, that at Smolensk, Napoleon thought of elevating Yorck to the dignity of a marshal of the empire, at the same time that at Vienna he caused Schwartzenberg to be named field-marshal.  The claims of these two commanders to the honour were by no means equal.

In both wings, disagreeable symptoms were manifested; with the Austrians, it was among the officers that they were fermenting; their general kept them firm in their alliance with us; he even apprised us of their bad disposition, and pointed out the means of preventing the contagion from spreading among the other allied troops which were mixed with his.

The case was quite the contrary with our left wing; the Prussian army marched without the least after-thought, at the very time that its general was conspiring against us.  On the right wing, therefore, during the time of combat, it was the leader who drew his troops after him in spite of themselves, while, on the left wing, the troops pushed forward their commander, almost in spite of himself.