Dual monarchy occurs when two separate kingdoms are ruled by the same monarch, follow the same foreign policy, exist in a customs union with each other, and have a combined military but are otherwise self-governing. The term is typically used to refer to Austria-Hungary, a dual monarchy that existed from 1867 to 1918 that spanned across parts of Central and Eastern Europe, but applies to other dual monarchies such as the Kingdom of Nejd and Hejaz. Dual monarchy is an uncommon form of government, and has been practiced few times in history, although many of the world's most powerful countries have been or are dual monarchies.
The idea had a great appeal in the political circles of Great Britain because of its success in integrating Scotland and England into Great Britain. The Stuart Kings of Scotland, starting with James VI, also were the heads of state of England, holding the English crown. After the 17th century brought three different civil wars, and a great deal of armed conflict, it was decided in 1707 to codify the unification of England and Scotland into the "perpetual" partnership promised by the Acts of Union. A similar series of historical events had earlier incorporated Wales into England. A century of personal union of the Crowns of Scotland and England also saw the monarchs use the parliaments of each nation against each other, and civil war, but generally benefitted the economic state of both nations. Indeed, it was the 1707 Acts which gave England and Scotland the name Great Britain. Despite its historical success, the proposal to merge Ireland into Great Britain with some form of home rule was bandied about for decades before finally coming to naught in the Irish War of Independence.
A dual monarchy is a stronger bond than a personal union, in which two or more kingdoms are ruled by the same person but there are no other shared government structures. States in personal union with each other have separate militaries, separate foreign policies and separate customs duties. In this sense Austria-Hungary was not a mere personal union, as both states shared a cabinet that governed foreign policy, the Army and common finances.[6]
^Saul, Nigel (May 1986), "Henry V and the Dual Monarchy", History Today, 36 (5): 39–43
^McKenna, J.W. (1965), "Henry VI of England and the Dual Monarchy: Aspects of Royal Political Propaganda, 1422–1432", Journal of the Warburg and Courtauld Institutes, 28: 145–162, doi:10.2307/750667, JSTOR750667, S2CID158251523
^Slagstad, Rune (2004), "Shifting Knowledge Regimes: the Metamorphoses of Norwegian Reformism", Thesis Eleven, 77 (1): 65–83, doi:10.1177/0725513604044236, S2CID145108242