When Germany occupied Denmark on April 9 1940 - the invasion was complete in about five hours - all communications with Iceland, a country in a personal union with Denmark under the king of Denmark, were severed. Iceland and Denmark had entered the personal union in 1918 voluntary in an agreement called Danish-Icelandic Act. According to the agreement, the personal union would be revised in 1940 and it would be end three years later if the two countries could not agree on the terms.
As Denmark was being occupied by the Nazis, the agreement came to an end by default. In a referendum on June 17 1944, the Icelanders decided to sever ties with the Danish monarchy and become a republic.
