St. Cyr being now for the moment in safety, reinforced the force facing Steingell with another French regiment and placed Wrede in command. At 4.30 a.m. on the 20th he fell unexpectedly upon Steingell, whose advance-guard, surprised in its bivouacs, was seized with a panic and dispersed. Buturlin says that 1800 men of 2 regiments of Chasseurs were captured, but as this would appear to be almost their whole strength, and they figure later as at least 2 battalions strong, this is doubtless an exaggeration. Steingell’s main body was not closely supporting the unlucky vanguard, and on its dispersal he hastily collected the remainder of his troops and retreated on Desna, where he crossed the Düna, while Wrede, having disposed of him, rejoined the main body of the French army. Besides St. Cyr, Legrand, the senior divisional commander, was wounded, and the temporary charge of the 2nd and 6th Corps devolved upon Merle. On the 21st he finally retreated from before Polotsk. Wittgenstein, hampered by lack of engineers and bridging material, could not establish a passage over the Düna until the 23rd. Only a detachment of cavalry under Colonel Rüdiger forded the river and skirmished with Merle’s outposts. To make the best of things Wittgenstein detached a division of all arms under General Sazonov to Desna to reinforce Steingell. The latter thereupon on the 23rd repassed the Düna, detached Major-General Vlastov with a force of 8 regular battalions, 1 militia battalion, 3 squadrons of Hussars, a regiment of Cossacks and 12 guns--about 5000 men in all--to observe Dünaburg, and with the rest of his force moved once more up the left bank of the river. On the same day Wittgenstein completed a bridge at Polotsk and began to cross. He had just been joined by two battalions of Novgorod militia, which he left with another militia battalion, 2 batteries, a detachment of regulars and some cavalry and Cossacks to garrison Polotsk. Merle retreated from before Polotsk in 3 columns, Legrand’s division moving on Bechenkowiczi, Wrede, with the remains of the 6th Corps and Corbineau’s cavalry, on Glubokoië to cover the road to Vilna, the remainder of the 2nd Corps and Doumerc’s Cuirassiers on Chasniki by way of Uchach and Lepel.