In the 1920s and 1930s, such ports were built in Gdynia and Hel, and the Polish Navy underwent a modernisation program under the leadership of Counter-Admiral Józef Unrug (Commanding Officer of the Fleet) and Vice-Admiral Jerzy Świrski (Chief of Naval Staff).
Ships were acquired from France, the Netherlands, and the United Kingdom, and the navy was to be able to secure the Polish supply lines in case of a war against the Soviet Union.
The navy was commanded by Counter Admiral Józef Unrug and his Chief of Naval Staff Jerzy Świrski.
Prior to the outbreak of World War II, on July 10, 1939, the defence of Polish Pomerania was reorganized into two separate commands under the leadership of Counter Admiral Unrug.
The submarine flotilla was left in Poland with the task of disrupting the enemy movement in the area of the Bay of Gdańsk, as well as to lay mines on the routes from Germany to East Prussian ports in the Operation Worek.
The Minelayer/Minesweeper Flotilla (Flotylla Minowców) was composed mostly of the so-called birdies (ptaszki, a nickname coined after the fact that all of the Jaskółka class ships were named after a different species of non-raptor birds).
After the war, some of the ships were returned to their owners, while the rest remained in active service and were pressed into the so-called Pinsk Flotilla.
In peacetime, the Riverine Flotilla of the Polish Navy, as it was officially called, operated on the Pina River, as well as on Pripyat and Strumień.
It served as a mobile reserve of the Border Defence Corps and was to support the front in case of a war with the Soviet Union.