- After the war from 1741 to 1743 had ended into a total catastrophe for Sweden, the Peace treaty of Turku was signed. The Swedish hat party had started the war without any real preparations, going as far as to declare the war on imperial Russia, before the Swedish troops were even mobilized. The border was again moved towards west. The border line followed now the western most distributary of Kymijoki and again the country was left without any border fortifications.

- With that in mind, the Swedes started again feverishly to fortify the border area. The area of Degerby (which was named Loviisa later on) was chosen initially in 1745 as a site to build a border fortification. The plan was agreed in 1746 to 1747, although the main fortification was to be build to Helsinki, which later on was known as Sveaborg and still remains as a tourist attraction on the coast of Helsinki. However the plan for a border fortification was agreed to be a good one in the area of Degerby (Loviisa), due to the favorable terrain. Additionally, the Svartholm island was to be fortified, which was located on the Debergy bay.

- The first few huts were constructed to Svartholm in the summer of 1746 and most likely the fortification plans were made by Augustin Ehrensvärd and thus accepting the fortification proposal made by A.J. Nordenberg. The fortification plan of Svartholm followed the same guide lines, which were agreed for Sveaborg fortification and the resemblance with these two is really striking. The construction how ever dragged on and the first defensive structures were started in 1752 and continued till 1766, when most of the bastions were nearly completed. After the year 1766, the construction efforts slowed down, but were hurried again after the relationship towards imperial Russia declined in 1772, due to the coup in Stockholm. This decline however didn't last long and in 1774 came an order to cease all construction efforts in Svartholm. The rest of the century the construction efforts dragged on, sometimes those were hurried and sometimes ceased, much like with every fortification plans that the Swedes made in the 18th century for Finland.

- When finally the imperial Russia was the attacking side in 1808, the Swedish fortifications in Finland were in a disgraceful state, Svartholm wasn't an exception to that. Additionally several misfortunes hit to the garrison and to the commanding officer Major Carl Magnus Gripenberg. First of all, the purpose of the Svartholm Sea Fortification was to stop the attack coming from the sea not from the land. Secondly, an attack during the winter was thought to be extremely unlikely. However, now both of those things had happened and during the second day of the Russian attack, the Russian troops were already looking at the Svartholm fortification, on the other side of the frozen bay. Due to the several misunderstandings and a competent Russian commander, the Svartholm garrison surrendered without a putting a fight, after being surrounded by the Russians less than a month and finding out, that their cannons were unable to fire effectively towards the mainland, where the Russian cannons were located.

- After these events, the strategic meaning of Svartholm declined, as it was located now inside of Russia, far away from the Swedish border. The final nail to the coffin came, when the combined British-French fleet sailed in the Gulf of Finland during the Crimean war, destroying several coastal fortifications and finally Svartholm too. 

- In the afternoon of 5th of July 1855, a huge explosion trembled the area and the Svartholm Sea Fortification which had never seen any real battles, was turned into a ruin.

- After the explosion, the Svartholm Sea Fortification was left alone and not until 1948 it was noted, that the fortification was in a really bad shape. However not much was done until in 1960's, when there was finally sufficient appropriation for the renovation work. Much has been done, but much is still in ruins or in a bad shape.

- Some of the storage rooms and interiors are in a nearly authentic condition, which were saved from the British and French. These areas are located in the inner fort.

- However, many sections from the outer fortification is either severely damaged or in a condition that the picture shows. The renovation work is still going on and I guess it's a matter of winning the time. Those red bricks can be found from all over the island, the explosion must have been a huge one.