Intriguingly, unlike most Swedish officers who had traditionally gone into foreign service under France, Cronstedt elected to fight for the British, and it is believed that by doing so he learned a great deal which he later put to use in his naval career, since Britain was at the time the foremost naval power in the world.

When Sweden in 1788 declared war on Russia he fought in the Swedish royal navy, now a lieutenant colonel.

In the peace treaty next year (1809), Sweden was forced to give up the territory of Finland (about half of the kingdom).

In order to find scapegoats for the loss of Finland the surrendering of Sveaborg became a convenient vehicle, and as Cronstedt was the responsible officer, he was charged with the whole catastrophe.

This narrative would make Cronstedt a convenient scapegoat, and deflect criticism from King Gustav IV Adolf.

After only three weeks of siege, negotiations between Carl-Olof Cronstedt and the commander of the Russian unit Jan Pieter van Suchtelen were held.

In Sweden, he was recognized as a traitor after the war, condemned to death in the court of Stockholm (later abolished on the initiative of the Russian emperor).

The Finnish War was seen as an embarrassment for Finland until Johan Ludvig Runeberg wrote the national romantic poem collection The Tales of Ensign Stål (Swedish: Fänrik Ståls sägner), which serves as a loose narrative of the conflict.

In these poems, Runeberg depicts the ordinary Finnish soldiers as fighting heroically, with their defeats being attributable not to any lack of courage or steadfastness on their part but rather to the incompetence and cowardice of their officers and the king himself.

This is particularly clear in the last three verses of the poem Sveaborg, which explicitly excuse the Finnish nation from blame for the loss of that fortress, while excoriating Cronstedt and calling for him to be subject to a form of damnatio memoriae: Hide away his family, do not mention his tribe, Do not turn away from his crime.

[1] The old legacy of Carl Olof Cronstedt was that Sweden was forced to give up half of its kingdom, whereas modern historians seem to explain the developments at Sveaborg by primarily smart psychological warfare combined with the widely spread low morale among Swedish officers.