Marshal MacDonald’s Tenth Corps comprised 32,500 men. Almost two-thirds of these troops were Prussians and in the early stages of the campaign they fought hard. Their commander, Lieutenant-General von Gräwert, stressed the need to restore Prussian military pride and regain the respect of the French for the army of Frederick the Great. Near the main estate of the Pahlen family at Gross Eckau on 19 July 1812 the Prussians defeated a Russian attempt to check their advance. Within a month of the war’s commencement the Prussians were in the vicinity of Riga, a huge Russian supply base, the largest city in the Baltic provinces and the key to the river Dvina.
Riga was not a strong fortress. Uniquely, the costs of its upkeep were borne not by the Russian state but by the Riga municipal government. In the century that had passed since the city was last seriously threatened its defences had been allowed to deteriorate. Only in June 1810 did the state take back responsibility for the city’s fortifications. During the next two years much was done to prepare Riga for a siege, but major weaknesses remained. Many of the key fortifications were out of date. The citadel was very cramped and hemmed in by residential areas. Riga’s suburbs had also grown greatly during the eighteenth century, occupying much of what had been open ground in front of the city’s outer walls.
The 19,000-strong garrison of Riga was commanded by Lieutenant-General Magnus von Essen. Most of these men came from reserve battalions and many were poorly trained. Sickness was rife in the garrison even before the siege began. Immediately on hearing that Napoleon had crossed the Neman Essen declared Riga to be in a state of siege: every household was ordered to store four months’ supply of food and any civilian departing the town was required to leave behind two able-bodied citizens in his household to help defend the city. In the fourth week of July, as the enemy approached Riga, Essen ordered that its western and southern suburbs be burned to the ground, in order to give the garrison a free field of fire beyond the walls. More than 750 buildings were destroyed, at an estimated cost of 17 million rubles. Nevertheless, it was generally agreed that Riga could not hope to hold out for more than two months against a serious siege.
If Napoleon had stopped in Vitebsk or Smolensk and dispatched part of his main army to help MacDonald, Riga would certainly have fallen. Without additional help, however, the French commander could not hope to take the city. A complete blockade line would have needed to stretch around Riga for more than 50 kilometres on both sides of the river Dvina. MacDonald’s 32,500 men on their own could never man such a line. In addition, Russian gunboats controlled the river and the British navy dominated the Baltic Sea and raided MacDonald’s communications along the coast. The French siege artillery, initially sent to Dünaburg, did finally arrive near Riga, but by the time it could be deployed for a serious siege the balance of forces on Napoleon’s northern flank was beginning to turn against the French.
Above all, this was because of the intervention of the Russian army in Finland. In the last week of August Alexander travelled to Åbo in Finland to meet the Swedish crown prince, Jean-Baptiste Bernadotte. The two leaders confirmed their alliance as well as arrangements for future military collaboration in northern Germany and Denmark. Of more immediate importance was the fact that Bernadotte released Alexander from his promise to use the Russian troops in Finland for a joint Russo-Swedish landing in Denmark in 1812 and urged him to send them to Riga instead. As a result, the Russian navy transported the bulk of the 21,000-strong Finland Corps to the Baltic provinces. Commanded by Count Fabian von Steinhel, these were mostly battle-hardened troops. By the second half of September their arrival in Riga was promising to end the stalemate on the northern front.1
Though Riga was Marshal MacDonald’s main preoccupation, he was also forced to keep one eye over his right shoulder towards Dünaburg and Polotsk. This was the area in which Lieutenant-General Count Peter von Wittgenstein’s First Russian Corps was operating. When Barclay’s army abandoned the camp at Drissa and headed for Vitebsk Wittgenstein’s corps was detached to block the roads leading north-westwards to Pskov, Novgorod and ultimately Petersburg. Wittgenstein’s main opponent was Marshal Oudinot, whose orders were to advance over the river Dvina and drive the Russians back on Pskov. In principle, this task should not have been beyond Oudinot, whose corps was more than 40,000-strong when it entered Russian territory. By contrast, Wittgenstein had only 23,000 men in First Corps and, though his forces were reinforced by two other small detachments, he was also responsible for containing any attempt by MacDonald’s right-wing division to advance from Dünaburg.2
