Carl Olof Cronstedt Carl - Olof Cronstedt the elder ( 3 October 1756 – 7 April 1820 ) was a Swedish naval commander responsible for the overwhelming Swedish victory at the Second Battle of Svensksund , one of the largest naval battles in history . He is often better remembered , however , as the commander of the fortress of Sveaborg ( ) during the Finnish war of 1808 , which was fought between Sweden and Imperial Russia , and ended in Cronstedt surrendering the fortress . The life of Cronstedt . Cronstedt was born on Botby mansion ( now a part of Helsinki ) in Finland 3 October 1756 . His parents were Johan Gabriel Cronstedt and Hedvig Juliana Jägerhorn af Spurila . He joined the army in 1765 and advanced to the rank of lieutenant in 1773 . Only five years later he was promoted to the rank of lieutenant colonel . When Sweden in 1788 declared war on Russia he fought in the royal navy . In 1790 he won a great naval victory against the Russian fleet at the naval battle of Svensksund ( in the Gulf of Finland ) . The naval battle is the greatest naval battle in the Baltic sea history . After the naval battle he was promoted to the rank of colonel and was appointed to naval state secretary . After further advances he was soon to become vice admiral . However , shortly after he was to be in disfavor of the new king and was appointed to be commander of Sveaborg . Cronstedt had desires to be commander of the whole royal fleet , not commander of some distant fortress in Finland . In 1801 , he was elected a member of the Royal Swedish Academy of Sciences , but was expelled in 1809 . After Finnish War Cronstedt lived rest of his life in his manor in Herttoniemi , near Helsinki . Siege of Sveaborg . Cronstedt surrendered the fortress to the Russian army after a siege of two months . The fortress had internationally received the reputation of being " the Gibraltar of the North " , and was by some assumed to be impregnable . 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 . Today however , many historians are re - evaluating the action of Cronstedt . His decision to surrender the fortress was a great humanitarian act , in order to prevent the children and women within being killed by the Russians ( many of the civilians from Helsinki had fled to the fortress and would likely have been be killed if Cronstedt had not reached agreements with the Russians ) . Furthermore , the war was doomed to a Swedish defeat already from the beginning . Sweden was not in the shape for war with no money or resources whatsoever . Cronstedt was the man to be blamed in order to save the dignity of King Gustav IV Adolf . Sveaborg in the Finnish war . War broke out 21 February 1808 on the initiative of the Russian empire . The timing was unusual , as wars were usually fought in summertime , and the temperature at that time was - 30 degrees Celsius ( - 22 F ) . Because of the cold winter , the poor condition of the Swedish army and the plan to retreat to the north , the Russian army faced poor resistance in Finland . So , the Finnish territory was overrun and half of the kingdom ( Finland ) was conquered in a few months . The Swedish main force retreated towards Sweden , leaving Sveaborg and Svartholm to defend themselves . The idea was that the fortresses would hold out and that reinforcements would arrive in the next summer . The fortress Svartholm surrendered already on 18 March . The siege of Sveaborg began in early March . After only three weeks of siege , negotiations between Carl - Olof Cronstedt and the commander of the Russian unit Jan Pieter van Suchtelen were held . The negotiations resulted in a deal , that if no reinforcements had arrived by 3 May , the fortress would unconditionally surrender . Unfortunately for the Swedes , the sea was still frozen in May 1808 and royal fleet could not arrive , therefore Sveaborg surrendered on 3 May . Suspected causes . Although much of the happenings are clear , some details are still held in darkness . One reason is that the sea was frozen and the royal navy could not arrive . Furthermore , the messengers sent to Stockholm were delayed by the Russians and arrived too late . It is also disputed if any troops would have arrived anyway , as Sweden had their troops tied with their southern enemy Denmark and their mighty ally France . Interesting though why Cronstedt did not succeed to buy more time and why any negotiations about surrendering were held in the first place , Sveaborg that was supposed to be the uninvadable " Gibraltar of the north " . These questions are more complicated to answer . Reasons : Unconfirmed theories . There are theories about the surrendering of Sveaborg that have never been confirmed or proven . Still , they continue to have support both amongst professionals and laymen . Despite the fact that the large picture is known , we should still consider the possibility of the following theories : Cultural impact . A short story " Under Siege " ( published in " Omni " , October , 1985 ) by George R . R . Martin takes place during the siege of Sveaborg , as well as in a dire future . The legacy of Cronstedt . The surrender of Sveaborg in undoubtedly one of the most important events in the history of Finland . Therefore Carl - Olof Cronstedt is naturally a central character of it . 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 ) . He alone was made responsible for the loss of Finland , and therefore ending one era in Swedish history . During the earlier , era of greatness Sweden was in the 17th century recognized as a major power in Europe , and now Sweden had become a shadow of its former self . Cronstedt was also by many condemned as a traitor in Finland . He was made a symbol of an embarrassing war and a failure to stop the Russian army . This war was for long an embarrassment for Finland until Johan Ludvig Runeberg wrote the national romantic poem collection " The Tales of Ensign Stål " . In this writing Runeberg paints the picture that the Finns fought bravely in the Finnish war and that everything was the fault of a few officers and the king . This was an encouragement for the Finnish national identity , in part built up on the hatred of Cronstedt . 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 . Today , Sweden and Finland are separate sovereign nations . It is therefore somewhat contradictory that Cronstedt has been seen as a traitor in Finland , when he is one of the main reasons for Finland being an independent nation . In 1990 ' s Cronstedt was remembered by naming a newly - built street in Helsinki after him . " Amiraali Cronstedtin ranta " ( Admiral Cronstedt ' s Quay ) is located about one kilometre from preserved admiral ' s manor in Herttoniemi .