Personal union in the context of "Christian X of Denmark"

A political union is a type of political entity which is composed of, or created from, smaller polities or the process which achieves this. These smaller polities are usually called federated states and federal territories in a federal government; they are called prefectures, regions, or provinces in the case of a centralised government. This form of government may be created through voluntary and mutual cession and is described as unionism by its constituent members and proponents. In other cases, it may arise from political unification, characterised by coercion and conquest. The unification of separate states which, in the past, had together constituted a single entity is known as reunification. Unlike a personal union or real union, the individual constituent entities may have devolution of powers but are subordinate to a central government or coordinated in some sort of organization. In a federalised system, the constituent entities usually have internal autonomy, for example in the setup of police departments, and share power with the federal government, for whom external sovereignty, military forces, and foreign affairs are usually reserved. The union is recognised internationally as a single political entity. A political union may also be called a legislative union or state union.A union may be effected in many forms, broadly categorized as:

• Incorporating union
• Incorporating annexation
• Federal union
• Federative annexation
• Mixed unions

The Polish–Lithuanian Commonwealth, also referred to as Poland–Lithuania or the First Polish Republic (Polish: I Rzeczpospolita), was a federative real union between the Kingdom of Poland and the Grand Duchy of Lithuania, existing from 1569 to 1795. This state was among the largest, most populated countries of 16th- to 18th-century Europe. At its peak in the early 17th century, the Commonwealth spanned approximately 1,000,000 km (390,000 sq mi) and supported a multi-ethnic population of around 12 million as of 1618. The official languages of the Commonwealth were Polish and Latin, with Catholicism as the state religion.

The Union of Lublin established the Commonwealth as a single entity on 1 July 1569. The two nations had previously been in a personal union since the Krewo Agreement of 1385 (Polish–Lithuanian union) and the subsequent marriage of Queen Jadwiga of Poland to Grand Duke Jogaila of Lithuania, who was crowned as Władysław II Jagiełło, jure uxoris King of Poland. Their descendant, Sigismund II Augustus, enforced the merger to strengthen frontiers of his dominion and maintain unity. As he remained childless, his death in 1572 marked the end of the Jagiellonian dynasty. It introduced an elective monarchy, whereupon members of domestic noble families or external dynasties were elected to the throne for life.

Real union is a union of two or more states, which share some state institutions in contrast to personal unions; however, they are not as unified as states in a political union. It is a development from personal union and has historically been limited to monarchies.

Unlike personal unions, real unions almost exclusively led to a reduction of sovereignty for the politically weaker constituent. That was the case with Lithuania and Norway, which came under the influence of stronger neighbors, Poland and Denmark respectively, with which each of them had shared a personal union previously.

The Kingdom of France is the historiographical name or umbrella term given to various political entities of France in the medieval and early modern period. It was one of the most powerful states in Europe from the High Middle Ages to 1848 during its dissolution. It was also an early colonial power, with colonies in Asia and Africa, and the largest being New France in North America geographically centred on the Great Lakes.

The Kingdom of France was descended directly from the western Frankish realm of the Carolingian Empire, which was ceded to Charles the Bald with the Treaty of Verdun (843). A branch of the Carolingian dynasty continued to rule until 987, when Hugh Capet was elected king and founded the Capetian dynasty. The territory remained known as Francia and its ruler as rex Francorum ('king of the Franks') well into the High Middle Ages. The first king calling himself rex Francie ('King of France') was Philip II, in 1190, and officially from 1204. From then, France was continuously ruled by the Capetians and their cadet lines under the Valois and Bourbon until the monarchy was abolished in 1792 during the French Revolution. The Kingdom of France was also ruled in personal union with the Kingdom of Navarre over two time periods, 1284–1328 and 1572–1620, after which the institutions of Navarre were abolished and it was fully annexed by France (though the King of France continued to use the title "King of Navarre" through the end of the monarchy).

The Kingdom of England was a sovereign state on the island of Great Britain from the 10th century, when it was unified from various Anglo-Saxon kingdoms, until 1 May 1707, when it united with Scotland to form the Kingdom of Great Britain, which would later become the United Kingdom. The Kingdom of England was among the most powerful states in Europe during the medieval and early modern periods.

Beginning in the year 886 Alfred the Great reoccupied London from the Danish Vikings and after this event he declared himself King of the Anglo-Saxons, until his death in 899. During the early tenth century, the various Anglo-Saxon kingdoms were united by Alfred's descendants Edward the Elder (reigned 899–924) and Æthelstan (reigned 924–939) to form the Kingdom of the English. In 927, Æthelstan conquered the last remaining Viking kingdom, York, making him the first Anglo-Saxon ruler of the whole of England. In 1016, the kingdom became part of the North Sea Empire of Cnut the Great, a personal union between England, Denmark and Norway. The Norman Conquest in 1066 led to the transfer of the English capital city and chief royal residence from the Anglo-Saxon one at Winchester to Westminster, and the City of London quickly established itself as England's largest and principal commercial centre.

Charles V (24 February 1500 – 21 September 1558) was Holy Roman Emperor and Archduke of Austria from 1519 to 1556, King of Spain (as Charles I) from 1516 to 1556, King of Sicily and Naples from 1516 to 1554, and also Lord of the Netherlands and titular Duke of Burgundy (as Charles II) from 1506 to 1555. He was heir to and then head of the rising House of Habsburg. His dominions in Europe included the Holy Roman Empire, extending from Germany to northern Italy with rule over the Austrian hereditary lands and Burgundian Low Countries, and Spain with its possessions of the southern Italian kingdoms of Sicily, Naples, and Sardinia. In the Americas, he oversaw the continuation of Spanish colonization and a short-lived German colonization. The personal union of the European and American territories he ruled was the first collection of realms labelled "the empire on which the sun never sets".

Charles was born in Flanders to Habsburg Archduke Philip the Handsome, son of Maximilian I, Holy Roman Emperor and Mary of Burgundy, and Joanna of Castile, younger child of Isabella I of Castile and Ferdinand II of Aragon, the Catholic Monarchs of Spain. Heir of his grandparents, Charles inherited his family dominions at a young age. After his father's death in 1506, he inherited the Habsburg Netherlands in the Low Countries. In 1516 he became King of Spain as co-monarch of Castile and Aragon with his mother. Spain's possessions included the Castilian colonies of the West Indies and the Spanish Main, as well as Naples, Sicily, and Sardinia. At the death of his grandfather Maximilian in 1519, he inherited the Austrian hereditary lands and was elected as Holy Roman Emperor. He adopted the Imperial name of Charles V as his main title, and styled himself as a new Charlemagne.

The Kingdom of Great Britain, officially Great Britain, was a sovereign state in Western Europe from 1707 to the end of 1800. The state was created by the 1706 Treaty of Union and ratified by the Acts of Union 1707, which united the Kingdom of England (including Wales) and the Kingdom of Scotland to form a single kingdom encompassing the whole island of Great Britain and its outlying islands, with the exception of the Isle of Man and the Channel Islands. The unitary state was governed by a single parliament at the Palace of Westminster, but the distinct legal systems—English law and Scots law—remained in use, as did distinct educational systems and religious institutions, namely the Church of England and the Church of Scotland remaining as the national churches of England and Scotland respectively.

The formerly separate kingdoms had been in personal union since the Union of the Crowns in 1603 when James VI of Scotland became King of England and King of Ireland. Since the reign of James, who had been the first to refer to himself as "king of Great Britain", a political union between the two mainland British kingdoms had been repeatedly attempted and aborted by both the Parliament of England and the Parliament of Scotland. Queen Anne (r. 1702–1714) did not produce a clear Protestant heir and endangered the line of succession, with the laws of succession differing in the two kingdoms and threatening a return to the throne of Scotland of the Roman Catholic House of Stuart, exiled in the Glorious Revolution of 1688.

The term Kingdom of Sardinia denotes the Savoyard state from 1720 to 1861. From 1720 to 1847, only the island of Sardinia proper was part of the Kingdom of Sardinia, while the other mainland possessions (principally the Duchy of Savoy, Principality of Piedmont, County of Nice, Duchy of Genoa, and others) were held by the House of Savoy in their own right, hence forming a composite monarchy and a personal union, which was formally referred to as the "States of His Majesty the King of Sardinia". This situation was changed by the Perfect Fusion act of 1847, which created a unitary kingdom. Regardless, historians often use "Sardinia" as a synecdoche to designate the whole Savoyard state from 1720. Due to the fact that Piedmont was the seat of power and prominent part of the entity, the state is also referred to as Sardinia–Piedmont or Piedmont–Sardinia, and sometimes erroneously as the Kingdom of Piedmont.

Before becoming a possession of the House of Savoy, the medieval Kingdom of Sardinia had been part of the Crown of Aragon and then of the burgeoning Spanish Empire. With the Treaty of The Hague (1720), the island of Sardinia and its title of kingdom were ceded by the Habsburg and Bourbon claimants to the Spanish throne to the Duke of Savoy, Victor Amadeus II. The Savoyards united it with their historical possessions on the Italian peninsula, and the kingdom came to be progressively identified with the peninsular states, which included, besides Savoy and Aosta, dynastic possessions like the Principality of Piedmont and the County of Nice, over both of which the Savoyards had been exercising their control since the 13th century and 1388, respectively.

The Acts of Union refer to two acts of Parliament, one by the Parliament of Scotland in March 1707, followed shortly thereafter by an equivalent act of the Parliament of England. They put into effect the international Treaty of Union agreed on 22 July 1706, which politically joined the Kingdom of England and Kingdom of Scotland into a single "political state" named Great Britain, with Queen Anne as its sovereign. The English and Scottish acts of ratification took effect on 1 May 1707, creating the new kingdom, with its parliament based in the Palace of Westminster.

The two countries had shared a monarch since the "personal" Union of the Crowns in 1603, when James VI of Scotland inherited the English throne from his cousin Elizabeth I to become (in addition) 'James I of England', styled James VI and I. Attempts had been made to try to unite the two separate countries, in 1606, 1667, and in 1689 (following the Glorious Revolution in 1688, and subsequent deposition of James II of England by his daughter Mary and her husband William of Orange), but it was not until the early 18th century that both nations via separate groups of English and Scots Royal Commissioners and their respective political establishments, came to support the idea of an international "Treaty of political, monetary and trade Union", albeit for different reasons.