The Russians, who had the navy of their Swedish opponents along with their Archipelago fleet trapped inside the Vyborg Bay, planned to attack the Swedish ships from different directions causing a decisive defeat on its navy before the wind would allow them to escape the trap.

On the night of July 2–3 the attack was commenced by Karl Heinrich von Nassau-Siegen who, with his coastal fleet of 81 ships of various sizes, sailed to meet with the Swedes stationed at the eastern strait of Björkösund.

[1] The strait beside the island of Kantasari, from which the Russians had to attack through, was narrow and was met with fierce fire at 23:00 on July 2 by the Swedish vessels.

A squadron of Lieutenant colonel Stedingk consisting of turumas was initially left to cover their withdrawal, but as the Russians chose not to pursue, they as well went off to the main Swedish vessels.

[3] The Swedes were successful in that they managed to hold off the Russian coastal fleet long enough for the preparations for the breakthrough to be set and so, on July 3, Gustav III of Sweden and his navy finally broke out, although with heavy losses.