Suomenlinna (in Finnish; before 1918 Viapori), or Sveaborg (in Swedish), is an inhabited sea fortress built on eight islands about 4 km southeast of the centre of Helsinki, the capital of Finland. Suomenlinna is a UNESCO World Heritage Site and is popular with tourists and locals who love it as a picturesque picnic spot. Originally named Sveaborg (Castle of the Swedes), or Viapori as it is called by the Finno-speaking Finns in 1918 for patriotic and nationalistic reasons, it was renamed Suomenlinna (Castle of Finland), although it is still known in Sweden under its original name as well as by the Swedish-speaking Finns.
The Swedish crown started building the fortress in 1748 as a protection against Russian expansionism. The overall responsibility for the fortification work was entrusted to Augustine Ehrensvärd. The original plan of the fortress-bastion was strongly influenced by the ideas of Vauban, the largest military engineer of the time, and the principles of the fortification style of the stellar fortress, although adapted to the group of rocky islands.
During the Finnish War, Sweden surrendered the fortress to Russia on 3 May 1808, paving the way for the occupation of Finland by Russian troops in 1809 and the subsequent cession of Finland to Russia at the end of the war. Russia held the fortress until Finland gained independence in 1918. Finland then ruled Suomenlinna through the Ministry of Defence until most of the fortress was placed under civilian control in 1973.
The Suomenlinna area in Helsinki is located to the south-east of the centre of Helsinki and consists of eight islands. Five islands are connected to each other by bridges or a sand bridge. Länsi Mustasaari (Switzerland: Västerswärthö) is connected to Pikku Mustasaari (Switzerland: Lilla Osterswärthörthö), which is connected to Iso Mustasaari (Switzerland: Stora Osterswärthörthö), which is connected to Susisaari (Switzerland: Vargo), which was connected to Susiluoto (Switzerland: Vargsker) by filling the separating waterway in the Russian period. This island, which has the highest concentration of fortifications, was renamed Gustavsvard (sword of King Gustav) (fi: Kustaanmiekka) during its construction by Sweden. There are three islands that are not united: Syarkkä (St. Longyoren), Lonnan (St. Lonnan) and Pormestarinluodot (St. Borgmästargundet). The total area of the plot is 80 hectares (0.8 km²).
Instead of the usual Finnish postal address (consisting of a street name and house number), Suomenlinna addresses consist of the letter code of the island, followed by the house number. For example, C 83 is house number 83 on Iso-Mustasaari (code C). The postal code for the Suomenlinna area is 00190.
At the beginning of the Northern War, Russia took advantage of Sweden's weakness in Ingria (Switzerland: Ingermanland) and took over the area from the Neva as well as the Swedish fortresses of Nyen and Nöteborg, built to protect it. In 1703 Peter the Great founded his new capital, St. Petersburg, in the very eastern corner of the Gulf of Finland. On the approach to it he built a fortified naval base Kronstadt. Russia soon became a maritime power and a force to be reckoned with in the Baltic Sea. The situation posed a threat to Sweden, which until then had been the dominant power in the Baltic Sea. This was clearly manifested in the use of naval forces during the Russian capture of Vyborg in 1710. The main Swedish naval base in Karlskrona was too far to the south to meet Sweden's new naval needs in the 18th century, which often led Swedish ships to reach Finland only after Russian ships and troops had either started or completed their spring campaigns.
The lack of coastal defence was acutely felt during the Russian landing in Helsingfors in the spring of 1713 and the failure of the Swedes in 1714 to block the Hanko Peninsula. The Russian naval campaign to the Swedish coast by the end of the Northern War further highlighted the need to develop the Finnish coastal defence. Immediately after the end of the war, the first plans to build a fleet on the archipelago and a base for it in Finland were started in Sweden. However, nothing happened in relation to Sveaborg until the end of the Russian-Swedish war of 1741-1743. Fortifications in Hamina and Lappeenranta remained unfinished while Hämeenlinna was being built on the supply base. Lack of funds, unwillingness to allocate funds for Finnish defence and the belief (which arose shortly before the war) that Russia would be pushed out of the Baltic Sea were the main reasons for the lack of progress.
The subsequent Russian-Swedish war of 1741-1743, which quickly changed from Swedish attack to Russian occupation of Finland, once again emphasized the importance of developing fortifications in Finland. The lack of a base of operations for the navy made it difficult for the Swedish navy to operate in the area. Other European states were also concerned about developments in relation to Russia, especially France, with which Sweden had concluded a military alliance. After a long debate, the Swedish parliament in 1747 decided both to strengthen the Russian border and to establish a naval base in Helsingfors as opposed to Kronstadt. The young Lieutenant Colonel Augustine Ehrensvard (1710-1772) was entrusted with the design of fortresses and the management of construction works.
Sweden began building fortresses in January 1748. Ehrensvard's plan included two fortifications: a sea fortress in Svartholm near the small town of Lovisa and a larger sea fortress and naval base (Sveaborg) in Helsingfors. The Ehrensvärd project for Sveaborg had two main aspects: a series of independent fortifications on several connected islands and, in the heart of the complex, a naval shipyard. In addition to the island fortress itself, the sea fortifications on the mainland would make it impossible for the enemy to get a beach head from which to attack the sea fortress. It was also planned to provide ammunition for the entire Finnish contingent of the Swedish Army and the Swedish Royal Navy. Additional plans were made to fortify the Hanko Peninsula, but they were postponed.
Construction, which began in early 1748, continued to expand, and by September there were about 2500 people in the fortresses. Initially, soldiers were placed in the vaults of the fortifications, while officers specifically built quarters integrated into the Baroque urban composition of the general layout. The most ambitious plan was left only half complete: the Baroque Place on Iso Mustasaari, partly modelled on the Place Vendôme in Paris. As the construction work continued, more residential buildings were built, many of which repeated the shape of the fortification lines. Ehrensvard and some other officers were passionate artists who created oil paintings representing a view of life in the fortress during its construction and giving the impression of a lively "fortress town".
Due to repeated Russian threats in 1749 and 1750, additional efforts were made to secure the Swedish naval units along the Finnish coast on the island's mainland. Using a military garrison located in Finland as a labour force, construction continued in 1750 with more than 6000 workers. Fortifications on Gustavsvärde were completed in 1751 and the main fortifications on Vargo were ready in 1754. The fortress was fully commissioned, although it was not completed. These achievements did not slow the pace of construction, and in 1755, 7,000 workers were building fortifications outside of Helsingfors, which at the time was home to about 2,000 people. Significant fortification work on islands south of the city brought new and unexpected significance. Sweden's participation in the Seven Years' War halted construction work in 1757, which also marked the end of Sveaborg's rapid construction phase.
This period in Swedish history was known as the Age of Freedom, during which the kingdom was under increased parliamentary control, divided into two political parties - the Hats and the Hats. Ehrensward was supported by Hats, so when Hats came to power in 1766, he was dismissed and replaced by Christopher Falkengrin, an ardent Hat Supporter. However, after 1769, when hats came to power again, Ehrensvärd was again placed at the head of the Swedish archipelago fleet in Finland, officially the army fleet ("army fleet"), and returned to Sveaborg. But additional progress in the construction of fortifications, when Ehrensvard died in 1772, was not achieved. Efforts to improve the fortress continued under Jacob Magnus Spraggporten, but his tenure was interrupted by disagreements with King Gustav III. Efforts were once again slowed down, as the garrisons were reduced, and in 1776 the commander of Sveaborga reported that he could not hold a tenth of the artillery placed in the fortress. Even at the beginning of the Russian-Swedish war of 1788, Sveaborg remained in incomplete condition.
The objects for the construction of ships for the fleet of the Swedish archipelago were built in Sveaborg in the 1760s. In 1764 the first three frigates of the archipelago were launched from there. Apart from building fortifications and ships, in 1770 Ehrensvärd began training naval officers in Sveaborg at his own expense. It took time until 1779 for a naval school to be officially founded there.