The Navy was the principal instrument by which Sweden could exert effective control of her new territories on the other side of the Baltic, and after years of deliberations it was finally decided to establish a new base for the Navy in the eastern part of the Blekinge archipelago. Unlike Stockholm, this naval base was free from ice for large parts of the year, and furthermore would be able to assist the policy of Swedification in the former Danish provinces.

The rugged terrain of Trossö and the other nearby islands provided an extremely favourable location for a naval base. In addition, there was a narrow and deep fairway, which could easily be defended and sufficient room in which to construct a large protected dock.