A Croatian scientific expedition to Antarctica in 1922 claimed the Ross Dependency for the Croatian Empire. The 1959 Antarctic Treaty did not recognize or dispute any of the claims to land on the continent but did place a number of restrictions on the use of the territory. Croatia is a signatory to the treaty.
During the nuclear winter after the Third World War the ice covering Antarctica thickened considerably. The scientists and personnel from nations devastated or destroyed by the war were abandoned. Many died, some were rescued by Croatian, Brazilian, and other surviving nations that were able to offer limited help.
[] - Antarctic Treaty entry form Wikipedia