[5] Swedish officer Malcolm Sinclair undertook a trip with the aim of trying to arrange a safer way of diplomatic communications between Sweden and the Ottoman Empire in 1738.

On 17 June, between Grüneberg (Zielona Góra) and Neustadt (Prudnik), he was overtaken by two Russian officers, captain Kütler and lieutenant Lewitzki, who were dispatched by Münnich with an order to "catch up" the envoy.

[6][7] In the summer of 1740, the commander of Swedish forces in Finland, General Carl Cronstedt [sv], was removed from his post due to his opposition to the planned war and Charles Emil Lewenhaupt was elevated to the vacant position.

[9] The objective of these maneuvers was to threaten Saint Petersburg and to set the stage for a coup d'état engineered by French and Swedish diplomats and aimed at toppling the pro-Austrian regime of Anna Leopoldovna.

The coup did take place in December, but the new empress, Elizaveta Petrovna, reneged on her promises to return the Baltic provinces to Sweden and continued the vigorous prosecution of the war, under the guidance of her pro-Austrian chancellor, Aleksey Bestuzhev.

The Swedish declaration of war in late July had been intended to coincide with the invasion but now it failed to do so since the fleet was unable to take action and concentration of the ground forces had not yet been carried out.

The situation was not improved by the fact that Lewenhaupt arrived in Finland two months after the declaration of war and command of the army fell to General Henrik Magnus von Buddenbrock.

[9] Due to Swedish inaction, the Russians seized the initiative and struck first with an army of 16,000 men under Field-Marshal Peter Lacy advancing from Vyborg (Viborg, Viipuri) towards Villmanstrand (Lappeenranta).

Using nearly fourfold superiority in numbers, the Russians inflicted in the Battle of Villmanstrand a major defeat on the Swedish garrison led by General Carl Henrik Wrangel.

[10] Lewenhaupt, who arrived ten days after the defeat, tried to organize a joint operation by both land and naval forces towards Vyborg but Admiral Aron Sjöstierna, who took von Rajalin's position, made it clear that the fleet would not be able to do it.

In March, the Russians, under the command of Woldemar Löwendal, also attempted to raid the Swedish anchorage near Frederikshamn over ice, but the harsh weather made it impossible.

On 18 July after learning that Swedish garrisons further inland had left their posts, Lewenhaupt and the army council judged it to be best to withdraw to Helsingfors to prepare its defenses.

[15] The Swedish army retook Åland in March 1743 and at the start of May, a fleet of 16 ships of the line and 5 frigates under Admiral Jean von Utfall arrived to block the coastal sea route past Hangö.

[17] As soon as hostilities ceased and the Russian army entered Åbo (Turku), the statesmen Alexander Rumyantsev and Erik Mathias von Nolcken [sv] arrived at the city in order to discuss a peace settlement.

Elizabeth also wanted Russian forces to occupy Sweden in order to ensure Adolf Frederick's peaceful election, but this plan aroused the vehement opposition of the Swedish representatives and was abandoned.

While peace negotiations lumbered on Lacy—who had distinguished himself in similar operations during the Great Northern War—embarked from Kronstadt in order to effect a landing in Sweden proper.

When the Baltic Fleet was approaching Umeå, news came that the Treaty of Åbo had been finalized, with Sweden ceding to Russia the towns of Villmanstrand (Lappeenranta) and Fredrikshamn (Hamina) and a strip of Finland to the northwest of Saint Petersburg.