Primarily built to protect Saint Petersburg, during the First World War Russia began to also fortify western Finland to guard against a possible German invasion.

This fortification project resulted in the forts of Örö, Utö and Lypertö among others, which then fell into Finnish possession after Finland's Declaration of Independence.

[2] In a further organization change in 1921 units on the western Gulf of Finland and Turku were separated from RT 1 and formed as Turku Independent Coastal Artillery Battalion (Turun Erillinen Rannikkotykistöpatteristo), consisting of the batteries on Örö, Russarö, Utö and Lypertö.

Utö fort fired 31 shots against the destroyers, identified as Gnevny class, hitting one of them.

[8] At the very beginning of the Continuation War the 7th Coastal Brigade took up positions in the Åland Islands.

With the Soviet Baltic Fleet trapped at the eastern end of the Gulf of Finland the threat for the brigade was low and the regiment headquarters were not established and only the most important forts were manned.

[9] During the Soviet Vyborg–Petrozavodsk Offensive in 1944 units from Åland Islands and Archipelago Sea were transferred east to reinforce the defences there.

After the Soviet offensive was halted on late summer of 1944 the defence of Åland Islands was reinforced to guard against a possible German invasion.

While there were no clashes between Finnish and German forces in Åland Islands or Archipelago Sea area, a force of three German ships that had left Finland late were allowed to pass by the Utö fort on 19.9.1944, the same day that Moscow Armistice was signed.

The German heavy cruiser Prinz Eugen along with escorts was patrolling of Utö, coming to a range of 10 kilometres (6.2 mi) at closest, when the three ships sailed by.

Utö fort was at battle stations during the event, and guns on the three German ships were similarly manned.

Åland Islands was separated from the regiment as part of the demilitarization, but Hanko Coastal Artillery Battalion and Gulf of Bothnia Coastal Guard were attached to it, resulting the regiments area of responsibility to stretch from Porkkala to Tornio on the Swedish border, an area of 1,000 kilometres (620 mi) long including 17 000 islands.

Even still it was necessary to use wood-fuelled harbor or lake tugs ill-suited for open sea to reach the required number.

Örö and Sommarö forts were also detached, while a new motorised coastal artillery battery was formed in the regiment in Janhua in Uusikaupunki.

A major change for signalling equipment was the adoption of digital messaging system.