United Kingdom cedes the United States of the Ionian Islands to Greece

Background. The United States of the Ionian Islands was a British protectorate from 1815. In 1862, the British Cabinet decided to cede the islands to Greece. This decision followed a Greek referendum electing Prince Alfred as king, partly hoping for the islands' transfer. The cession was intended to support the newly installed King George I.

Treaty and Union. Representatives of the UK, Greece, France, and Russia signed the Treaty of London on 29 March 1864, pledging sovereignty transfer upon ratification. On 21 May, the British departed, and the islands became Greek provinces. On 28 May, the Lord High Commissioner proclaimed the union with Greece, though Britain retained the port on Corfu.

Political Context. The Ionian Islands had a bicameral legislature. In 1850, a resolution for union with Greece was proposed in the Ionian parliament. During British rule, William Ewart Gladstone recommended reunion with Greece, causing friction with the British government. The islands were a federation with a Supreme Council of Justice established in 1818.