Kotka Southern Finland Finland

After retreating to Svensksund, Gustav decides to make a stand here.

The Swedish coastal fleet is reinforced by forty ships under Lieutenant-Colonel Carl Olof Cronstedt after the escape from Vyborg.

Gustav decides to lead the fight personally and divides his forces into four brigades under lieutenant-colonels Carl Olof Cronstedt, Claes Hjelmstjerna, Victor von Stedingk, and Jakob Törning.

Von Stedingk is to lead the center consisting of two hemmema (Styrbjörn and Starkotter) and two udema (Torborg and Ingeborg) archipelago frigates, the brig Alexander, fifteen galleys, two half-galleys, and eleven cannon or mortar longboats.

Törning has the command of the right wing consisting of thirty-nine gun sloops and twenty-two gun yawls while Hjelmstierna's left wing has thirty gun sloops and fourteen gun yawls supported by twelve gun sloops and yawls from Cronstedt's brigade.

The rest of Cronstedt's brigade, consisting of the turuma Norden, one galley and thirty-six gun sloops and yawls, is to remain in reserve and guard against a possible Russian flanking maneuver.

Artillery batteries are constructed on the skerries of Kråkskär (between the center and right wings) and Sandskär (between the center and left wings).

The preparations are completed on July 8.

The Russian coastal fleet consists of nine archipelago frigates, thirteen xebecs, two mortar ships, four gun prams, three floating batteries, twenty-six galleys, six schooners, four cutters, seventy-seven gun sloops and one hundred and twenty-one lightly armed boats.

The Russian fleet carries around nine hundred cannons compared to four hundred and fifty Swedish cannons and has clear superiority in both number of ships and men.

The Russian coastal fleet is eager to attack, especially on 9 July, the anniversary of Catherine the Great's proclamation as Empress of Russia.

Recognizing the failure to decisively defeat the Swedish archipelago fleet a year earlier at the same location, the Russian commander, Prince Charles of Nassau-Siegen, chooses to commit his whole force from the south.

This is done to prevent the Swedes from escaping to the shelter of Svartholm fortress, since Nassau-Siegen is expecting a clear victory, having numerical superiority in ships and artillery as well as in men.

On the morning of July 9 Gustav III abruptly names Lieutenant-Colonel Cronstedt as his flag-captain after relieving Colonel George de Frese from his duties.

The reason for this sudden change is likely that de Frese has been in favor of withdrawing from Svensksund to a more favorable location while Cronstedt has advocated fighting the Russians at Svensksund.

The Russian flagship signals the attack at 08:00 on July 9.

By 9:30 the first ships have reached firing distance in the western flank but soon after fighting spreads throughout the battle lines.

The Swedish right wing under Lieutenant Colonel Törning meets with increasing resistance as the Russian left wing opposing him gets reinforced.

However, the Swedes are able to move ships from their reserves to support their right wing with a counterattack that manages to lead the Russian left wing into disorder.

Meanwhile, the increasingly strong southwesterly wind forces the Russian center deeper between converging Swedish lines.

After no Russian ships are seen approaching from Frederikshamn, the Swedes are able to release more ships from the reserves to bolster the Swedish left wing led by Lieutenant Colonel Hjelmstierna.

Half of Hjelmstierna's ships are sent to the rear of the Russian fleet through a narrow passage between Legma and Kutsalö, which in turn forcea the Russian right wing to deploy accordingly.

However, movement to the back of the line is read as a signal to withdraw by the Russian left wing, which starts its retreat leaving the Russian center to face the Swedes alone.

By the evening it has become apparent that the Swedes are victorious even though the Russian center, consisting of their galleys and largest ships, continuea to fight despite unfavorable winds and battle damage.

At this time the Swedes are able to fire at the Russian ships from the front as well as from both sides and several Russian ships start drifting into the Swedish battle line.

Other Russian ships catch fire or are intentionally set on fire while a few are beached to avoid sinking.

At 20:00 Naussau-Siegen orders the Russian fleet to withdraw and to destroy drifting Russian ships in order to keep them from being captured.

Strong winds make the withdrawal difficult and several ships fail to make it.

A few of the Russian ships ignore the order to withdraw and instead keep fighting until they sink.

Fighting doesn't end until 22:00.

The wind calms down during the night and several Russian ships try to escape under the cover of darkness, but Swedish gun sloops and yawls are sent to hunt them down and this type of fighting continues until 09:00 on the morning of July 10, 1790.

The Russians have lost at least seventy-four hundred of fourteen thousand men; fourteen hundred dead and wounded and six thousand captured, compared with Swedish losses of one udema, five minor vessels and three hundred men, though other sources place the number of dead and wounded Swedes to around six hundred.

Among the Russian ships lost are ten "archipelago frigates" (sail/oar hybrids) and xebecs, nine half-xebecs (schooners), sixteen galleys, four gun prams and floating batteries, seven bomb vessels, five gun sloops and several other small vessels.

Along with twenty-one other ships, the Swedes have captured the Catarina, Nassau-Siegen's flagship.

The battle of Svensksund is the biggest naval battle ever fought in the Baltic Sea: five hundred ships (including supply ships and other ships not involved in combat), over thirty thousand men and several thousand cannons.

At Svensksund, the Swedes boast to have destroyed forty percent of the Russian coastal fleet.

It qualifies among the largest naval battles in history in terms of the number of vessels involved.

The defeat at Svensksund encourages Russia to negotiate with Sweden, eventually signing the Treaty of Värälä on August 14, 1790.

Neither side gains any territory, however all provisions in the peace treaty of Nystad from 1721 that formally infringe  upon Swedish sovereignty are cancelled.

After the war the Russians will start a massive fortification program on the eastern, Russian, side of the Kymi river, building the sea fortresses Fort Slava, Fort Elisabeth and the land fortress Kyminlinna.

The forts will later grow into the port city of Kotka.