In November of 1939, Soviet forces invaded Finland with the intention of bringing additional territory into the communist fold. Even though the Soviet forces vastly outnumbered the Finns, Finnish troops put up a heroic resistance and the conflict was resolved 4 months later with the loss of ~11% of Finland’s pre-war territory. Thus when Nazi Germany launched its invasion of the Soviet Union on June 22, 1941 the Finns were quick to lend their support to the Nazis in an effort to regain their lost territory.
Flowing from this cooperation was the use of Finnish naval forces to screen against Soviet naval forces while German ground forces advanced through the Baltic states. In one such operation, Operation Nordwind, one of Finland’s two capital ships, the Ilmarinen, struck a mine and sank with 271 casualties. The loss of the Ilmarinen on September 13, 1941 was devastating to the tiny Finnish Navy. For a force consisting of only 3,800 officers and sailors, the loss represented 7% of Finnish naval forces. By comparison, less than .8% of the US Navy perished in the attack on Pearl Harbor.
The Ilmarinen had been built in the 1930s as a coastal defence ship for the purpose of defending the numerous islands and islets of Finland’s Baltic coastline. Video of the ship in 1938 can be seen here (the Ilmarinen is the first ship shown in the video). The ship saw service in the Winter War defending the Finnish coast against the Soviet invaders and later shelled Soviet forces after the beginning of the German invasion.
Even though the Finns initially sided with the Nazis, they fought not for ideology, but for self-preservation. In September 1944, the Finns established a separate peace with the Soviets and engaged the Nazis in open combat in the Lapland region until the Nazis withdrew to Norway in April 1945.