The Protectorate, in English history, was the period during which Oliver Cromwell was declared 'Lord Protector' of the Commonwealth of England, Scotland, and Ireland, under the terms of a constitutional document entitled the 'Instrument of Government', which had been drawn up by a group of his army officers. Under the Protectorate, Cromwell was dictator, backed by the army with a council of state and an ineffectual single-house Parliament under his control. Using a royalist uprising for a pretext, he swept away the traditional shire governments in 1655, replacing them with military districts administered by army officers.
The Protectorate is associated with the most rigidly enforced puritan legislation. Religious toleration was extended to Jews and most Protestant sects, but not to Anglicans or Catholics. After Cromwell's death in 1658, the Protectorate devolved upon his son, Richard Cromwell, who was unable to control the army and resigned in May, 1659. After a chaotic interregnum, the Restoration of the monarchy was effected in May 1660, largely through the initiative of General George Monck.
The British revived the term after 1815, in ordering and validating their de facto occupation of Corfu and the seven Ionian islands during the last days of Napoleonic hegemony. The islands were constituted by the Treaty of Paris in 1815 as the independent 'United States of the Ionian Islands' under British protection.
Other British protectorates followed. In 1894 Prime Minister William Gladstone's government officially announced that Uganda was to become a British Protectorate, where Muslim and Christian strife had attracted international attention. The British administration installed carefully selected local kings under a program of indirect rule through the local oligarchy, creating a network of British-controlled civil service.
The League of Nations established protectorates for "responsible" European powers in various areas of the non-European world.
In international law, a protectorate is a dependent area in which a metropolitan power has acquired control of the area's foreign relations and defense but which the metropolitan power has not annexed. The dependent area, thereby, is not under the sovereignty of the metropolitan power. Those born in such a dependent area, viz., a protectorate, are not nationals of the metropolitan power, and the area remains foreign for purposes of the metropolitan power's domestic law. However, the metropolitan power of a protectorate may exercise its jurisdiction - not sovereignty - in such an area in as ample a manner as if the metropolitan power had gained the area by conquest or cession.
Some agencies of the United States government, particularly the United States Environmental Protection Agency, has used the term protectorate to refer to insular areas of the United States such as Puerto Rico and the Virgin Islands. However, the agency responsible for the administration of those areas, the Office of Insular Areas within the United States Department of Interior contends that this usage is incorrect, and that a change in a U.S. insular area’s status cannot come about simply by colloquial references in a Federal agency’s correspondence or even in the regulations that that agency issues. Such a change occurs only after discussions on point within the Federal Executive Branch and specific enactment by Capitol Hill. According to the OIA, The U.S. insular areas are not protectorates as international usage commonly understands that term, e.g. the United Kingdom’s one-time colonial protectorates, protected states and protectorates