The Swedish era

In the first half of the 18th century, Sweden lost its regional superpower status and its most significant eastern fortresses. The government considered it vital to improve the defences in the eastern part of the kingdom, Finland. In 1747, the Estates took the decision to build a central fortress complete with naval base in Helsinki and a border fortress in Degerby off Loviisa.

In the following year, fortification work began on the Susiluodot islands off Helsinki, the location of present-day Suomenlinna. Over the next few years, the fortification plan was gradually reduced, and resources were focused on building the maritime fortress part of the plan. In 1750, the fortress was named Sveaborg (‘Castle of Svea’), rendered phonetically in Finnish as Viapori. Soon work also began on a dry dock to serve a shipyard that would build warships for the Archipelago Fleet.

The active construction phase on the fortifications of Viapori lasted for just over four decades. Even so, the fortress was actually never quite completed as planned, even though the original aim was to build it from start to finish in only four years. There were two major interruptions to the work in the course of those four decades. The Seven Years War (the ‘Pomeranian War’, 1756–1763) stopped work on the fortress. In the late 1760s, work was again suspended because of a change in the political climate caused by the ‘Caps’ party coming into power.

Viapori was not engaged in military action in the 18th century. It did serve as a naval base during the Russo-Swedish War of 1788–1790 (‘Gustav III’s War’), but there was no combat in its immediate vicinity.

In the Russo-Finnish War of 1808-1809 (the ‘War of Finland’), Viapori came under siege soon after the war began in 1808. Though actual combat amounted to minor skirmishes, Commandant C.O. Cronstedt decided to surrender. The maritime fortress was taken over by the Russians, and a new era began on Viapori.