At Polotsk the Tzar left the army. It was a wise step, for he was useless at the front, while at the seat of government his presence would be invaluable. Paulucci accompanied him, and was replaced by Major-General Yermólov, while Colonel Toll became Quartermaster-General. On bidding farewell Alexander bade Barclay not to endanger his army, for it was the only one that Russia possessed. This injunction undoubtedly made a strong impression upon Barclay, and is the best explanation of his irresolution some weeks later. On July 20th Napoleon’s plan was definitely formed. He would turn Barclay’s left by throwing forward the Guard and the 4th and 6th Corps to Bechenkoviczi on the road to Vitebsk, while Murat and Ney contained the Russians in front, and Oudinot occupied Drissa and threatened their right. Barclay, however, was already moving. On the 19th Uvarov’s cavalry corps started from Polotsk, and by the 23rd the entire army was collected round Vitebsk. There Barclay heard that Bagration had reached Mohilev, and wrote begging him to hasten his march on Orsha. He sent Major-General Tuchkov IV with his infantry brigade, 3 cavalry regiments and 1 of Cossacks, towards Babinovichi on the Orsha road, and Lieutenant-General Count Ostermann-Tolstoï, who had succeeded Shuvalov (retired through illness) with the 4th Corps, a brigade of Dragoons, and the Hussars of the Guard and of Sumi, towards Ostrovno on the way to Bechenkoviczi. The rest of the Russian army remained at Vitebsk to rest and reorganise. The advance-guard of the French 4th Corps was already at Bechenkoviczi. Oudinot had two divisions at Polotsk and the third at Drissa. Lobau was to Eugène’s left rear, with Ney some 20 miles farther back: Murat, with Nansouty’s corps, was near Bechenkoviczi; Montbrun was moving up the right bank of the Düna towards Vitebsk; Napoleon with the Guard was at Kamen, about 21 miles from Bechenkoviczi. The unhappy 6th Corps was toiling along the Glubokoïe-Polotsk road. At 6 a.m. on the 25th Murat’s and Ostermann’s outposts collided near Ostrovno. Here the road, coming from Vitebsk between woods, made a sharp turn to the right, and another equally abrupt to the left some way farther on. The leading Russian regiment, the Guard Hussars, charged headlong and, sabring the French pickets, blundered up against Piré’s brigade in the rear. It was driven back with heavy loss upon a horse battery which was following, and in the confusion the French captured six guns. Ostermann, who was some way behind, sent forward the Sumi Hussars to check the French advance. He then formed for battle, with Choglokov’s division deployed across the road and Bakhmetiev’s in columns behind, and in this order the 4th Corps marched forward to Ostrovno, and took position between the woods.