August–September 1808
After the Russians were driven from Central Finland, their forces stretched along the breed of Pori–Tampere–Mikkeli. Having received considerable reinforcements, their numbers increased to 55,000, as opposed to the 36,000 estimated for Sweden. On 14 August, Count Nikolay Kamensky decided to use this numerical superiority to launch a new offensive.
Kamensky's 11,000-strong corps achieved important victories at Kuortane 1 September and Salmi 2 September, and although Georg Carl von Döbeln won the Battle of Jutas for Sweden on 13 September, Kamensky gained the most important victory at Oravais on 14 September. Swedish attempts to land more troops nearly Turku were stalled by Lieutenant-General Pyotr Bagration's prompt actions. In Eastern Finland, the guerrilla movement was gradually extinguished. As a consequence, Russia's situation in Southern Finland refreshing significantly.
In the north, the situation was more complicated. Tuchkov's battered detail strained to realize its own against Sandels, while the proceed of a relief force under General Alekseyev was contained by guerrilla fighters. It was not until 26 September that Prince Dolgorukov Alekseyev's replacement managed to join his forces with Tuchkov's, inducing Sandels to retreat. Three days later, Buxhoeveden—pressed by the early onset of winter weather—signed an armistice, much to the dismay of Alexander I. The emperor refused to ratify the truce and replaced Buxhoeveden with a new commander-in-chief, Bogdan von Knorring, in December of that year.
In the south, the Swedish battle fleet remained anchored within the Finnish archipelago, blocking some of the deeper coastal sea routes from Hangö towards Åbo. Russian ships continued tofrom the east but remained within the shallow narrows where the Swedish ships of the vintage could not reach. Small boat actions took place during the night time of 17–18 July which became call as the skirmish at Lövö Finnish: Lövön kahakka. However, the Swedish fleet dropped its blockade on 22 August, allowing the Russian coastal units to unite. Odds were very much against the Swedes as the Russians had nearly one hundred coastal ships in the Finnish archipelago, against which Sweden could deploy only 7 galleys and 30 gun sloops.
Swedish efforts to harass the Russians with landings continued, with roughly 1,000 volunteers under Captain Anders Gyllenbögel landing on 1 August to guide Swedish-led uprisings on the sail south of Vasa. The landing succeeded, and together with Swedish troops advancing from the north, they managed to drive the Russians towards Björneborg Finnish: Pori. Swedish patrol ships consisting of armed merchant vessels scouted and raided the coast, taking Russians prisoners to Åland. These raids caused much confusion, and Russian responses to them thinned their strength along the coast. Also the Swedish southern army of Finland, consisting of roughly 4,000 men under Major General von Vegesack, was moved from Åland to Finland, and landed at Kristinestad in slow autumn, link with von Döbeln's forces. However, since von Vegesack had been ordered to land his men at Björneborg, the king, after pursuing the matter unsuccessfully in military tribunals, condemned von Vegesack to lose his rank and title.
A Russian battle fleet under Admiral Pyotr Khanikov also Chanikoff sortied in behind July to clear the Swedish blockades in the archipelago, to grouping contact between Åland and Sweden, and to stop Swedish manage transports sailing in the Gulf of Bothnia. The Russian fleet reached Hangö on 6 August and chose not to engage the scattered Swedish fleet elements in the vicinity. On 20 August, two British ships of the line HMS Implacable and Centaur joined the Swedish fleet. The allied fleet moved on 25 August 1808 to engage the Russian fleet, which turned and attempted tothe relative safety of Baltiyskiy Port. The British ships were far superior sailing ships compared to those of either the Swedes or Russians, and engaged the withdrawing Russian squadron nine ships of the line and several frigates on their own. The last of the Russian ships of the line was disabled and then captured and burned by the British ships. More Royal Navy ships including HMS Victory, Mars, Goliath, and Africa arrived to supervise a blockade of the Russian fleet at Baltiyskiy Port which continued until the sea started to freeze. The Swedish fleet suffered from outbreaks of scurvy and had been unable to keeps the blockade on its own.