A personal union is a combination of two or more monarchical states that have the same monarch while their boundaries, laws, and interests remain distinct. A real union, by contrast, involves the constituent states being to some extent interlinked, such as by sharing some limited governmental institutions. It differs from a federation in that each constituent state has an independent government, whereas a federal state is united by a central government. The ruler in a personal union does not need to be a hereditary monarch.
The term was coined by German jurist Johann Stephan Pütter, introducing it into Elementa iuris publici germanici (Elements of German Public Law) of 1760.
Personal unions can arise for several reasons, such as:
inheritance through a dynastic union, e.g., Louis X of France inherited France from his father and Navarre from his mother decolonization, where ex-colonies install the monarch of the former colonizing power as their own upon becoming independent, e.g., several former members of the British Empire (then becoming Commonwealth realms) autonomization, e.g., instead of annexing Finland into the Russian Empire, Alexander I of Russia organized Finland as an autonomous grand duchy and acted as its head of state
They can also be codified (i.e., the constitutions of the states clearly express that they shall share the same person as head of state) or non-codified, in which case they can easily be broken (e.g., by the death of the monarch when the two states have different succession laws).
The concept of a personal union has only very rarely crossed over from monarchies into republics.
There are currently two personal unions in the world: the 15 Commonwealth realms, who share Charles III as their head of state, and one of the co-princes of Andorra being the President of France.
Monarchies in personal union Africa Congo Free State and Belgium Personal union with Belgium from 1885 to 1908, when the Congo Free State became a Belgian colony. The only sovereign during this period was Leopold II, who continued as king of Belgium until his death a year later in 1909.
Asia Near East During the reign of Sargon II and Sennacherib, Babylon and Assyria were two countries connected via the same ruler.
Georgia Kingdom of Iberia and Colchis were connected power of the monarch in the years 300–90 BCE (Pharnavazid dynasty). Kingdom of Pontus and Colchis were connected power of the monarch in 109 BCE-64 CE. 1000–1010 Kingdom of Abkhazia and Iberia ruled by Bagrat III. In 1010 it united (together with the annexed Kakheti kingdom) into a single Kingdom of Georgia. Kingdom of Kakheti and Hereti were connected power of the monarch in 1020s–1104. Principality of Mingrelia and Principality of Abkhazia in the 1557–1660 years under the rule of the House of Dadiani. Kingdom of Kartli and Kingdom of Kakheti united under the rule of a single monarch in 1513–1518 (David X), 1625–1633 (Teimuraz I), 1648–1658 (Rostom), 1723 (Constantine II/III), to finally unite the Kingdom of Kartli-Kakheti in 1762 under the reign of Heraclius II and his descendants. Kingdom of Imereti and Principality of Guria united under the rule of a single monarch in 1681–1683 (George III Gurieli), 1701–1702, 1713–1714 (Mamia III Gurieli) and 1716 (George IV Gurieli).
Goryeo Personal union with Shenyang in the Mongol Empire (1308–1313; 1345-1351) As King of Goryeo (高麗國王) and Prince/King of Shenyang (瀋陽王) in 1308–1310 As King of Goryeo and Prince/King of Shen (瀋王) in 1310–1313, 1345-1351
King Chungseon of Goryeo reigned as King of Goryeo in 1298 and 1308–1313 and as King of Shenyang or King of Shen from 1307 (according to the History of Yuan) or 1308 (according to Goryeosa) to 1316. At that time, Goryeo had already become a vassal of the Mongol Empire and the Mongol imperial family following the Mongol invasions of Korea and the Goryeo royal family had established strong ties by intermarrying with the Mongol imperial family. Because King Chungseon was a very powerful man during the reign of Külüg Khan, Külüg Khan gave him a new title on top of his kingship of Goryeo, the Prince/King of Shenyang, in 1307According to the History of Yuan (specifically, ). or 1308 specifically mentioned as thanks to his efforts of bringing the Khan to power.According to Goryeosa (specifically ).
However, he lost his power in the Mongol imperial court after the death of the Külüg Khan. Because the Mongol Empire made Chungseon abdicate the crown of the Goryeo in 1313, the personal union was ended. King Chungsuk, Chungseon's eldest son, became the new King of Goryeo. In 1316, the Mongol Empire made Chungseon abdicate the crown of Shen in favour of Wang Ko, one of his nephews, resulting in him becoming the new King of Shen.
Following Wang Ko's death, Chungmok of Goryeo and Chungjeong of Goryeo were also dual rulers of both Goryeo and Shenyang from 1345-1351.
Europe Albania Medieval Albanian Kingdom personal union with the Kingdom of Naples (1272–1368).
Andorra Due to Andorra's special government form resulting from the Paréage of 1278, it is a diarchy with co-princes. One of them is the Bishop of Urgell; the other was originally the Count of Foix. It is through this feudal co-prince system that the Principality has entered partial personal union with:
Kingdom of Navarre (1479–1620, then integrated into France). Kingdom of France (1589–1792, 1814–1815, 1815–1830, 1830–1848).
In 1607, the feudal co-prince was Henry IV of France, who issued an edict that his position should be held by the French Head of State. While the new government did not take up the title during the French Revolution, all polities of France since 1806 regardless of their government form have accepted that their head of state is an ex officio co-prince. This led to personal unions with:
First and Second French Empires (1806–1814, 1815 and 1852–1870). Second, Third, Fourth and Fifth Republics of France (1848–1852, 1870–1940, 1944–1958, since 1958). French State (known as Vichy France, 1940–1944, in dispute with Free France).
Austria Personal union with Lands of the Bohemian Crown (1260–1276, 1306–1307, 1438–1439, 1453–1457, and 1526–1918). Personal union with Lands of the Hungarian Crown (1437–1439, 1444–1457, and 1526–1918).
Bohemia Personal union with Poland under Polish occupation (1003–1004). Personal union with Poland (1296–1306) and Hungary (1305). Personal union with Luxembourg (1313–1378, 1383–1388). Personal union with Hungary 1419–1437 (Sigismund of Luxemburg) and 1490–1526 (Jagellon dynasty). Personal union with Austria and Hungary 1438–1439 (Albert II of Germany), 1453–1457 (Ladislaus the Posthumous) and 1526–1918 (disputed during 1619–1620 by Frederick of Palatine and 1741–1743 by Charles Albert).
Brandenburg Personal union with the Principality of Ansbach (1415 to 1440, 1470 to 1486). Personal union with the Duchy of Prussia from 1618, when Albert Frederick, Duke of Prussia, died without male heirs and his son-in-law John Sigismund, Elector of Brandenburg, became ruler of both countries. Brandenburg and Prussia maintained separate governments and seats of power in Berlin and Königsberg respectively until 1701, when Frederick I consolidated them into one government.
Catalonia Personal union, as the Principality of Catalonia, with the Kingdom of Aragon (1173) the Kingdom of Mallorca (1229), and the Kingdom of Valencia (1238) constituting together the Crown of Aragon (1162-1715) Personal union with the Monarchy of Spain (1516-1714) Personal union with the Kingdom of France (1641-1652)
Croatia
Personal union with the Kingdom of Hungary (1102–1918).
Denmark Personal union with: Norway (986–995, 1000–1014, 1028–1035, 1042–1047, 1380–1397, 1397–1523 (Kalmar Union) and 1524–1814 (Denmark–Norway)). England (1013–1014, 1018–1035 (North Sea Empire) and 1040–1042). Duchy of Estonia (1240-1329, 1340–1346). Sweden (1397–1523) (Kalmar Union). Duchy of Schleswig (1086–1364, 1460–1864) and County/Duchy of Holstein (1460–1864). County of Oldenburg (1448, 1667–1773). County of Palatinate-Neumarkt (1443–1448). Rügen (1814). Duchy of Saxe-Lauenburg (1814–1864). Iceland (1918–1944).
England Personal union, as Kingdom of England, with: Denmark (1013–1014, 1018–1035 (North Sea Empire) and 1040–1042). Duchy of Normandy (1066–1087, 1106–1144, 1154–1204/1259). County of Anjou (1154–1204). Much of France (Angevin Empire) (1154–1214). Aquitaine (1154–1453). Principality of Wales (1284–1542). Kingdom of France (1422–1453). See also: Dual monarchy of England and France. Lordship of Ireland (1171–1542) and Kingdom of Ireland (both legally subordinate) (1542–1649, 1660–1707). Monarchy of Spain (1556–1558). Kingdom of Scotland (1603–1649, 1660–1707).1 Principality of Orange and the Dutch Republic (1689–1702).
1: After 1707, see Great Britain below.
France Personal union, as part of the Angevin Empire, with the Kingdom of England (1154–1214). Personal union with the Kingdom of England (1422–1453). See also: Dual monarchy of England and France. Personal union with the Kingdom of Naples under the rule of Charles VIII (1495) and Louis XII (1501–1504). Personal union with the Duchy of Milan under the rule of Louis XII (1499–1500 and 1500–1512) and Francis I (1515–1521 and 1524–1525). Personal union with the Kingdom of Scotland under the rule of Francis II (1559–1560). Personal union with the Polish–Lithuanian Commonwealth under the rule of Henry III (1574–1575). Personal union with the Kingdom of Navarre (1284–1328 and 1589–1620). Partial personal union with Andorra since 1607 (the French head of state is one of two joint heads of state in Andorra). Personal union with the Principality of Catalonia (1641-1652). Personal union under Napoleon with Italy (1805-1814) and the Confederation of the Rhine (1806-1813).
Note: The point at issue in the War of the Spanish Succession was the fear that the succession to the Spanish throne dictated by Spanish law, which would devolve on Louis, le Grand Dauphin — already heir to the throne of France — would create a personal union that would upset the European balance of power; France had the most powerful military in Europe at the time, and Spain the largest empire.
Great Britain Before 1707, see England and Scotland.
Personal union with Kingdom of Ireland (1707–1801) Personal union with Electorate of Hanover (1714–1837) Personal union with the Kingdom of Corsica (1794–1796)
After 1801, see United Kingdom below.
Hanover
Personal union with Great Britain and Ireland from 1714 to 1801. Personal union with the United Kingdom from 1801 to 1807 and again from 1814 to 1837, when differing succession laws resulted in Queen Victoria ascending the British throne and her uncle Ernest Augustus that of Hanover. The personal union was interrupted from 1807 to 1813 when Hanover was merged into the Kingdom of Westphalia during the Napoleonic Wars. A few months after the Battle of Leipzig, the Kingdom of Hanover was established, a continuing state.
Holy Roman Empire Personal union with the Kingdom of Sicily from 1194 to 1254 under the Hohenstaufen dynasty. Personal union with Spain from 1519 to 1556 under Charles V. Personal union with Hungary 1410–1439, 1556–1608, 1612–1740 and 1780–1806. Personal union with Kingdom of Naples (1714–1735), Kingdom of Sardinia (1714–1720), Kingdom of Sicily (1720–1735).
Hungary Personal union with Croatia 1102–1918 (see above for details). Personal union with Poland and Bohemia 1305.