Kingdom of Iceland

The Kingdom of Iceland (Icelandic: "Konungsríkið Ísland"; Danish: "Kongeriget Island") was a constitutional monarchy that had a personal union with Denmark. The kingdom was created on 1 December 1918. It lasted until 17 June 1944 when a national referendum created the Republic of Iceland.
The Act of Union, signed on 1 December 1918, allowed Iceland to create its own flag, declared its neutrality and asked Denmark to help with its foreign affairs and defense interests.
The Nazi German occupation of Denmark in the early-1940s broke off their communications. As a result, the Althing named themselves the head of state and said that Iceland would no longer need Denmark's help. The island was later occupied by British and American forces. This lasted until World War II ended.
The monarchy held an constitutional referendum from 20 and 23 May 1944. The option to establish a new republican constitution won with 98.5% of the vote. Christian X of Denmark sent a message of congratulations to the Icelandic people.