Following the armistice of the Finnish Winter War on March 6th, 1940, Hanko was leased to the Soviet Union as a military base for a period of 50 years.
In 1947 the Soviet Union renounced the lease formally in the Paris peace treaty of 1947, the territory had however remained in Finnish control since the base was evacuated on December 2nd 1941, during the Continuation War. As a curiosity it can be noted that the short Russo-Finnish front queer over the base of the peninsula on the Finnish side was held by volunteer troops from Sweden.
The role of the Hanko naval base was replaced by Porkkala in the armistice between Finland and the Soviet Union of September 19th 1944.
The Hangon Regatta has been a traditional fixture on the Finnish social scene. Many people who have very little or no interest in sailing, attend nevertheless in order to party and absorb the atmosphere.
See also: World War II