The coastal fortifications built on the northern and southern shores of the Gulf of Finland around the First War were lumped together under the name of Peter the Great's naval fortress. Originally, this fortress only consisted of the Central Station between the Porkkala headland and the island of Naissaari in Estonia, and the Archipelago Station between the Porkkala and Hanko headlands. In 1913, Nicholas II confirmed that the name of Peter the Great's naval fortress be used for the Central and Archipelago Stations; however, no decision was ever taken to incorporate Viapori with this fortress.

 

The focus is shifted to islands off the coast

 

Following the annihilation of the Russian Baltic Fleet in the Russo-Japanese War in 1905, the Russians felt compelled to develop the coastal defenses in the Gulf of Finland, including a mine laying capacity, and to build a fleet of fast torpedo boats. However, no consensus was ever reached on the plan. The army proposed that the outdated fortress of Viapori be closed, and new fortifications be built on the mainland. The navy, for its part, was opposed to the proposal, holding the view that the fortress provided significant protection for the Viapori naval port, planned to be the main base for torpedo boats. The conflict ended in a compromise under which the fortress island was not closed but the focus of costal defenses was moved to the islands off Viapori.

 

Between 1909 and 1910, the Russians were preparing a new defense plan for the Gulf of Finland, with the strengthening of the Viapori’s defenses against seaborne assaults and the fortifications in the mainland against land operations being part of the plan. Fortifications were built on the islands of Rysäkari, Katajaluoto, Harmaja, Kuivasaari, Isosaari, Santahamina and Itä-Villinki off Viapori by 1915, tasked with protecting the Viapori naval port located at Katajanokka and in the water area off Kruunuvuori. The plan also included the construction of a series of land fortifications encircling Helsinki. Viapori was part of an extensive coastal defensive system along the Gulf of Finland, constructed to defend St. Petersburg.

 

Viapori becomes the main base of the Baltic Fleet

 

The First World War highlighted Viapori’s position as the main base of the Baltic Fleet. Peter the Great’s port, planned to be constructed in Tallinn, was never completed, leading to Viapori being made the backup harbour of Russia’s Baltic Fleet.