Complex sentence: Immediately after the war had ended first plans were set into motion in Sweden to construct a coastal fleet and a base of operations for it to Finland however nothing with regards to Sveaborg took until place until the end of Russo-Swedish War of 1741--1743.
Split into simpler sentences: Immediately after the war had ended first plans were set into motion in Sweden to construct a coastal fleet and a base of operations for it in Finland. However, nothing with regard to Sveaborg took until place until the end of Russo-Swedish War of 1741--1743.