The battle of Ostrovno (25-26 July 1812) was a rearguard action fought between Ostermann-Tolstoy's rearguard of Barclay de Tolly's 1st Western Army and Murat's advance guard of the Grande Armée. The Russians were eventually forced to retreat into Vitebsk, but they held up the French for two days.
Napoleon's early efforts after the invasion of Russia had been focused against General Bagration's 2nd Western Army, but by early July Bagration had escaped from the French trap and was heading east towards the Dnieper. Davout was given the task of preventing Bagration from moving north while Napoleon focused on Barclay de Tolly's 1st Western Army. In early July this army reached the fortified camp at Drissa on the Dvina River, but it quickly became clear that this camp was untenable. The Russians decided to abandon it and move east towards Vitebsk.
Murat, who had been given the task of watching the Russians at Drissa while Napoleon focused on Bagration, reported the Russian retreat on 19 July. Napoleon's first instinct was that the Russians would head for Polotsk, half way between Drissa and Vitebsk, and he ordered his army to concentrate at Kamen (south-east of Polotsk). By 21 July Napoleon realised his mistake and ordered his troops to move east to Biechenkovski, where he still hoped he might be able to intercept Barclay de Tolly. On 24 Napoleon reached Biechenkovski, but on the same day Russian prisoners confirmed that Barclay de Tolly had already reached Vitebsk.
At this stage Barclay de Tolly was actually planning to stand and fight. He believed that Bagration would soon be approaching from the south and wanted to hold on at Vitebsk until the two Russian armies could unite. General Osterman-Tolstoy, who had only recently been given command of 4th Corps, was given the Ingermanland and Nezhinsk Dragoons, Life Guard Dragoons, Sumsk Hussar and Life Guard Hussar regiments and ordered to delay the French west of Vitebsk.
The French advance was led by General Nansouty's 1st Cavalry Corps, with Marshal Murat close behind. The first clashes, between Nansouty's advance guard and Russian cavalry, were won by the Russians. Murat's advance guard then arrived, and this time the French had the best of the fighting.
Osterman-Tolstoy deployed his troops in two lines just to the west of Ostrovno, defending the main road to Vitebsk. The 11th Division (Nikolay Bakhmetyev) was posted in the front line with the 23rd Division (Aleksey Bakhmetyev) in the second line. The Ingermanland Dragoons were posted on the left of the Russian front line, the Sumsk Hussars in the second line.
On the French side General Saint Germain's cavalry division was on the left, part of Bruyères's cavalry division formed the right and the rest of his cavalry along with the 8th Légere were in the centre. General Delzons' division was further west on the road.
The battle started with a Russian cavalry attack, led by the Ingermanland Dragoons. This ended in failure when the French cavalry counterattacked. In the centre the French skirmishes were taking a heavy toll of the Russians. The Russian infantry attempted to drive them back, but once again the French cavalry defeated them.
The French were less successful when they attempted to attack. The Russians had a strong defensive position with their flanks secured by woodland, and the famously stoic Russian infantry refused to retreat even when suffering heavy losses to artillery fire. Osterman-Tolstoy's own attacks were also repulsed, and eventually the arrival of French reinforcements forced him to retreat east.
Overnight both sides received reinforcements. The Russians successfully held a new position at Kakuvyachino, three miles to the east of Ostrovno, for most of the day, before finally retreating to Vitebsk. Ostermann-Tolstoy's men had help up the French for two days, but at heavy cost, losing 834 dead, 1,855 wounded and around 1,000 missing or captured.
By the end of the fighting the scene appeared to be set for the first major battle of the campaign. Barclay de Tolly's men were still at Vitebsk and Napoleon was approaching from the west.
Further south Bagration had been unable to force his way past Davout's corps at Mogilev (23 July 1812). This meant that he would no longer be able to join Barclay de Tolly at Vitebsk. When this news reached him Barclay de Tolly decided to continue the retreat east, but if Napoleon had attacked on 27 July the Russians would still have been forced to fight. Instead Napoleon decided to pause for a day in order to allow more of his troops to take part in the battle. This would prove to be a disastrous decision. By the time Napoleon was ready to attack on 28 July the Russians had withdrawn from Vitebsk and were heading for Smolensk and the long-hoped for battle of Vitebsk was nothing more than a series of skirmishes with the Russian rearguard.