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Map of Sveaborg fortress in 1808.

The Siege of Sveaborg was a short siege by Russia that took place at Sveaborg (Finnish language: Suomenlinna ) in early 1808, during the Finnish War.


Week before the war began Sveaborg's commander Admiral Carl Olof Cronstedt received a letter from the King Gustav IV Adolf which required him to fit for operations and acquire crews for 2 hemmema type archipelago frigates and over 70 smaller gunboats or yawls. Additionally letter demanded that the fortress of Sveaborg must be defended to the bitter end and should withdrawing from the fortress be necessary then the bulk of the coastal fleet which had been docked at the fortress for the winter as well as all the supplies had to be destroyed by burning them down.[1]

The siege

Russian forces under Friedrich Wilhelm von Buxhoeveden laid siege to Sveaborg after the fall of Helsingfors on March 2, 1808. However the Russian force which had captured Helsingfors consisted only of roughly 2 000 men who had no chances in even just harassing the fortress. It took well into mid March before Russians had concentrated 4 000 men to area under General Jan Pieter van Suchtelen who started more effective sieging of Sveaborg by building first artillery batteries for the siege artillery in its vicinity. In early April Russians had amassed 6 500 men and 59 artillery pieces, some of which had been taken from Svartholm fortress after it surrendered, to besiege Sveaborg.[2]

Defenders at Sveaborg often fired at the Russian cossack patrols on the ice around the fortress but without any practical results. Instead of attacking the numerically inferior besieger Swedes were content to stay behind their fortifications and prepare for the Russian assault by sawing a ditch to the open the ice around the fortress. First Russian barrages were fired on 19 March and continued until 21 March after which first attempts to negotiate were made. Cronstedt agreed on not firing at the town of Helsingfors in exchange of Russians keeping their artillery batteries away from that direction. This suited the Russians since it allowed them to lodge their troops in Helsingfors without a danger of being shot at by the Swedish artillery.[3]

March 23 Cronstedt parleyed with Russian representatives on the island Lonnan where Russians demanded the surrender of the fortress. After the Swedish refusal to comply Russians started another barrage at the fortress on 25 March which lasted until 1 April. Russian surrender demand was repeated on 2 April. Russians resorted to cunning psychological warfare to convince the officers in the fortress to surrender. Former Swedish subject, Johan Samuel Hagelström, received special commendation from the Tsar for his actions in getting Sveaborg to surrender. Certain officers' wives who lived in Helsingfors were allowed and encouraged by the Russians to visit the husbands in Sveaborg also played their parts. Perhaps the most important person in the Russian efforts to use cunning to force a surrender was the trusted advisor of Cronstedt, Colonel Fredrik Adolf Jägerhorn.[4]

In the negotiations that continued on 2 April Cronstedt suggested a truce at least until 13 May 1808. Russians responded positively but demanded that truce would last only until 3 May and that meanwhile they would occupy several of the fortified small islands around the main fortress of Sveaborg. When discussing the matter with his officers Cronstedt noted that according to his reckoning fortress had ammunition only for two weeks left and that men were getting sick. When asked about the fleet Cronstedt refused to torch it stating that it would be a disaster if the fortress would survive and there would be no fleet left.[5]

On April 6 Cronstedt agreed with Jan Pieter van Suchtelen, the Russian commander in Helsinki, on an honorable capitulation on May 3 in case Swedish reinforcement didn't reach Sveaborg by then. The Swedish couriers bearing the requests for reinforcements were delayed by the Russians and didn't reach Stockholm until May 3, the same day Cronstedt capitulated and surrendered the fortress to the Russians, along with 7,500 soldiers and a fleet of 94 ships. Even if the couriers had arrived earlier, Sveaborg probably could not have been relieved by the fleet, as the winter was unusually cold and the Baltic sea was still partially frozen at the time. Fortress lost 6 men dead and 32 wounded as well as couple of broken roofs and windows as the result of Russian actions in the siege.[6]

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.

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. Cronstedt's failure to buy more time as well as the question why such a truce had been necessary in the first place remain at least partially obscure given the Sveaborg's reputation of being the impregnable "Gibraltar of the north".


  • Sveaborg is a bastion fortress, built on principles applied in Europe. This architectural type was considered as the world's most modern in those days. However, bastion fortresses were normally built in central Europe, where the land is flat. As the Finnish archipelago isn't flat at all (the height changes are huge) Sveaborg didn't fit the location very well. As the architecture of a bastion fortress is relying on a symmetrical defense, Sveaborg had lots of weaknesses. The Gibraltar of the north was therefore not a very justified name.
  • Although the Russian army was at first much smaller (2000 men, 60 cannons) than the forces at Sveaborg (6000 men, 734 cannons), more reinforcements arrived all the time. By the time of the negotiations, the Russian army was larger than the defending force.
  • The fortress had earlier received very poor funding. Since its completion in 1791, Sveaborg received no extra financial support from the government (the reason for that is still a mystery, but naturally related to the weak Swedish economic situation). The military equipment was in an unsatisfactory condition. Most of the supplies were of bad quality and the fortress was lacking most supplies.
  • The cannons too, were old and partially obsolete. This meant that their range was shorter than that of the Russian artillery (which is a problem if cannons are stationed on a fortress). The fortress was unable to return fire on the Russian troops that were bombarding the fortress heavily. Furthermore the fortress was lacking cannons; having not even half the number of cannons that were supposed to be on the fortress (almost 1600 cannons).
  • Cronstedt claimed that the fortress was in shortage of gunpowder. This has been disputed by some historians as opinions diverge around what should have been sufficient daily battle usage of gunpowder.
  • The reason for the limited time of one month is that the negotiations were more or less dictated by the Russians. The Russian army was better supplied and had better artillery. The Russian army gave Sveaborg only one month to get reinforcements.
  • Sveaborg was facing perhaps the world's most mighty army. Even if the fortress had been well built and well supplied, it is arguable if it could have withstood the war.
  • Sveaborg had never been fully completed. Only the fortifications on the islands had been constructed but none of the land side defenses included to the original plans by Augustin Ehrensvärd were constructed.
  • Unwillingness by the Swedes to burn or shell the town of Helsingfors to the ground gained Russians a strong base of the operations against the fortifications and would have been according some historians the best solution for preventing Russians from successfully besieging the fortress.

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:

  • The war came surprisingly, and the civilians at Sveaborg were not evacuated in time. They were mostly families of the officers, 2000 civilians. It is possible that the commander, Cronstedt, wanted to save the lives of the women and children at Sveaborg. In those days fortress invasions were very bloody stories and no-one was usually spared.
  • Cronstedt was even believed to have been bribed by the Russians. Despite recent research this is still a popular theory today. During the Finnish war, two fortresses were located in south Finland: Sveaborg and Svartholm (located nearer to the Russian border). The commander of Svartholm C.M.Gripenberg surrendered the fortress quite immediately to the Russian army. Shortly after he was employed by the Russian army. This was seen by many as bribery, as he was given a good position in the Russian army (officers changing side was very common during this war). Therefore Cronstedt was also a target for suspicions of bribery. However, the suspicions of Cronstedts bribery have never been confirmed. It is true that he as well was given a pension (Cronstedt refused to join the Russian army and retired shortly after the war) by the Russian emperor, but the amount of money was normal and not much. There were no reports afterwards of any great wealth of Cronstedt. Further, Cronstedt continued after the war to carry his Swedish medals and wanted to defend his actions in front of a Swedish court himself, but was then finally advised to stay in Finland.
  • It is believed that the Russian army was using war-psychology skillfully. Many of the officers families were living in Helsinki and the Russian army was using the letter correspondency cunningly to convince the officers at Sveaborg that the Russian army was substantially larger than it was and that the whole kingdom of Sweden had been invaded. Many of the officers were suppressing Cronstedt to surrender. Afterwards Cronstedt was criticised for not reckoning the enemy force properly (the reason is still unknown).

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. It is a reworking of an original stroy "The Fortress" written by Martin as a history paper for college. Both "The Fortress" and "Under Siege" in which time travelers form a dystopian future affect the outcome, can be found in Martins collection of short stories "Dreamsongs" published by Bantam.


The capture of Sveaborg helped the Russian conquest of Finland greatly, as it removed the threat of a counterattack from the south and west. To Sweden it was a devastating blow as it made the resupply of the battered Finnish army much more difficult. It was considered by many as one of the major reasons (if not the major reason) Finland was lost. Cronstedt was subsequently considered a traitor by many Swedes and Finns, notably Johan Ludvig Runeberg in his epic The Tales of Ensign Stål.

Amongst other things Russian captured bulk of the Swedish archipelago fleet. This included 3 hemmema and 7 turuma type archipelago frigates, 25 gun sloops, 51 gun yawls and various other ships. This had immense effect to the war in Finnish archipelago especially since the chance of the Russian battlefleet to successfully engage joint Swedish and British battlefleets in the open sea was marginal. Before Russians were able to deploy their newly captured fleet an explosion happened at Sveaborg on 3 June 1808 which together with the fire that broke out afterwards caused considerable damage to the ships at Sveaborg destroying amongst other things six of the seven captured turuma type archipelago frigates.


  1. Mattila (1983), p. 238.
  2. Mattila (1983), p. 238-239.
  3. Mattila (1983), p. 239.
  4. Mattila (1983), p. 240-241.
  5. Mattila (1983), p. 241-242.
  6. Mattila (1983), p. 242-243.


  • Mattila, Tapani (1983) (in Finnish). Meri maamme turvana [Sea safeguarding our country]. Jyväskylä: K. J. Gummerus Osakeyhtiö. ISBN 951-99487-0-8. 

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