From Riga on August 7th Essen again made a sortie and captured Schlock, which was then retaken by the Prussians. On the 23rd Essen decided to make a general attack upon the Prussians, who lay observing the city, extended from Schlock to Thomsdorf on the Düna, a distance of 42 miles. A column under Lewis was to make the real attack upon Eckau, while a detachment under Major-General Veliaminov demonstrated towards Mitau, and Rear-Admiral von Müller with a flotilla of sloops attacked Schlock. The Prussian posts at Dahlenkirchen on the Düna were driven back, with some loss, by Lewis, but Veliaminov’s demonstration had no results, though von Müller captured Schlock. On the 26th Grawert, having collected his scattered detachments, drove Lewis back into Riga; and Schlock and Dahlenkirchen were reoccupied. The losses in these actions, combined with sickness, considerably weakened the garrison. On the other hand, they proved that the Prussians were not strong enough even to blockade the place. Macdonald sent a brigade of Grandjean’s division to reinforce them, and prepared to bring up the rest of it at need. After this both sides lay inactive until September 18th, when there was some more indecisive skirmishing about Schlock. The Prussians were now commanded by Lieutenant-General Yorck, Grawert being invalided. Between the 20th and 22nd, Count Steingell’s corps from Finland, which had landed at Revel on the 10th, entered Riga. It had sustained some losses by shipwreck, and part of the troops were detained by contrary winds, so that Steingell had with him only a little over 10,000 men and 18 guns. Nevertheless, the force in Riga was now over 20,000 strong, and an attempt could be made to execute the Tzar’s orders. On the 26th accordingly Steingell with his own troops and a division under Lewis moved out upon Dahlenkirchen. It was easily occupied, and on the 27th Steingell advanced upon Eckau, where Yorck had collected several regiments. His superiority in artillery enabled him to hold Steingell in check until the arrival of Lewis, when he retired behind the Aa, abandoning Bausk. While Steingell was pushing back Yorck, Essen directed a column of 2000 men and 6 guns upon Mitau from Riga, while a flotilla came up the Aa. Essen’s hope was to destroy the siege train, which, however, was not there. He ordered Steingell to support the advance with 3000 men and 6 guns, under Colonel Ekeln. On the 28th Yorck, being not yet joined by Hunerbein’s brigade (Grandjean’s division), ordered General Kleist to abandon Mitau and come to reinforce him. This Kleist did, and on the 29th the Russians occupied the place without opposition. But meanwhile Yorck, reinforced by Kleist and Hunerbein, took the offensive against Steingell’s weakened force and began to drive it back. There was some not very vigorous fighting along the Aa, as the result of which the Prussians gained a foothold on the farther bank.