Crown of the Kingdom of Poland in the context of "Lithuania"

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.

The Polish–Lithuanian union was a relationship created by a series of acts and alliances between the Crown of the Kingdom of Poland and the Grand Duchy of Lithuania that lasted for prolonged periods of time from 1385 and led to the creation of the Polish–Lithuanian Commonwealth, or the "Republic of the Two Nations", in 1569, which ended in 1795 with the Third Partition.

Lviv (/ləˈviːv/ lə-VEEV or /ləˈviːf/ lə-VEEF; Ukrainian: Львів [ˈlʲviu̯] ; Polish: Lwów [ˈlvuf] ; see below for other names) is the largest city in western Ukraine, as well as the fifth-largest city in Ukraine, officially with a population of 723,403 (2025 estimate). It serves as the administrative centre of Lviv Oblast and Lviv Raion, and is one of the main cultural centres of Ukraine. Lviv also hosts the administration of Lviv urban hromada. It was named after Leo I of Galicia, the eldest son of Daniel, King of Ruthenia.

Lviv (then Lwów) emerged as the centre of the historical regions of Red Ruthenia and Galicia in the 14th century, superseding Halych, Chełm, Belz, and Przemyśl. It was the capital of the Kingdom of Galicia–Volhynia from 1272 to 1340, when it went to King Casimir III the Great of Poland in a war of succession. In 1356, Casimir the Great granted it town rights. From 1434, it was the regional capital of the Ruthenian Voivodeship in the Kingdom of Poland. In 1772, after the First Partition of Poland, the city became the capital of the Habsburg semi-autonomous Polish-dominated Kingdom of Galicia and Lodomeria. From 1918, between the wars, the city was the centre of the Lwów Voivodeship in the Second Polish Republic. There it flourished in culture, industry and academia such as the Lwów School of Mathematics, the Lwów Historical School (Polish: lwowska szkoła historyczna) and the Lwów School of Economics. After the German-Soviet invasion of Poland in 1939, the massacre of Lwów professors took place, and Lwów was eventually annexed by the Soviet Union.

The Siege and Battle of Vienna took place at Kahlenberg Mountain near Vienna on 12 September 1683 after the city had been besieged by the Ottoman Empire for two months. The battle was fought by the Holy Roman Empire (led by the Habsburg monarchy) and the Polish–Lithuanian Commonwealth, both under the command of Polish King John III Sobieski, against the Ottomans and their vassal and tributary states. The battle marked the first time the Commonwealth and the Holy Roman Empire had cooperated militarily against the Ottomans. The defeat was a turning point for Ottoman expansion into Europe, after which they would gain no further ground. In the ensuing war that lasted until 1699, the Ottomans would cede most of Ottoman Hungary to Leopold I, Holy Roman Emperor.

The battle was won by the combined forces of the Holy Roman Empire and the Polish–Lithuanian Commonwealth, the latter represented only by the forces of the Crown of the Kingdom of Poland (the march of the Lithuanian army was delayed, and they reached Vienna after it had been relieved). The Viennese garrison was led by Feldzeugmeister of the Holy Roman Imperial Army Ernst Rüdiger Graf von Starhemberg, an Austrian subject of Holy Roman Emperor Leopold I. The overall command was held by the senior leader, the King of Poland, John III Sobieski, who led the relief forces.

Nicolaus Copernicus (19 February 1473 – 24 May 1543) was a Renaissance polymath who formulated a model of the universe that placed the Sun rather than Earth at its center. The publication of Copernicus's model in his book De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres), just before his death in 1543, was a major event in the history of science, triggering the Copernican Revolution and making a pioneering contribution to the Scientific Revolution. Though a similar heliocentric model had been developed eighteen centuries earlier by Aristarchus of Samos, an ancient Greek astronomer, Copernicus likely arrived at his model independently.

Copernicus was born and died in Royal Prussia, a semiautonomous and multilingual region created within the Crown of the Kingdom of Poland from lands regained from the Teutonic Order after the Thirteen Years' War.

Kyiv, also Kiev, is the capital and most populous city of Ukraine. Located in the north-central part of the country, it straddles both sides of the Dnieper River. As of 1 January 2022, its population was 2,952,301, making Kyiv the seventh-most populous city in Europe. Kyiv is an important industrial, scientific, educational, and cultural center. It is home to many high-tech industries, higher education institutions, and historical landmarks. The city has an extensive system of public transport and infrastructure, including the Kyiv Metro.

The city's name is said to derive from the name of Kyi, one of its four legendary founders. During its history, Kyiv, one of the oldest cities in Eastern Europe, passed through several stages of prominence and obscurity. The city probably existed as a commercial center as early as the 5th century. A Slavic settlement on the great trade route between Scandinavia and Constantinople, Kyiv was a tributary of the Khazars, until its capture by the Varangians (Vikings) in the mid-9th century. Under Varangian rule, the city became a capital of Kievan Rus', the first East Slavic state. Completely destroyed during the Mongol invasions in 1240, the city lost most of its influence for the centuries to come. Coming under Lithuania, then Poland and then Russia, the city would grow from a frontier market into an important centre of Orthodox learning in the sixteenth century, and later of industry, commerce, and administration by the nineteenth.

The Autonomous Republic of Crimea is a de jure administrative division of Ukraine encompassing most of Crimea that was unilaterally annexed by Russia in 2014. The Autonomous Republic of Crimea occupies most of the peninsula, while the City of Sevastopol (a city with special status within Ukraine) occupies the rest.

The Cimmerians, Scythians, Greeks, Goths, Huns, Bulgars, Khazars, Byzantine Greeks, the state of Kievan Rus', Kipchaks, Italians, and Golden Horde Mongols and Tatars each controlled Crimea in its earlier history. In the 13th century, it was partly controlled by the Venetians and by the Genoese, and in the late 15th century, it was partly under Polish suzerainty. They were followed by the Crimean Khanate and the Ottoman Empire in the 15th to 18th centuries, the Russian Empire in the 18th to 20th centuries, Germany during World War II, and the Russian Soviet Federative Socialist Republic, and later the Ukrainian Soviet Socialist Republic, within the Soviet Union during the rest of the 20th century until Crimea became part of independent Ukraine with the breakup of the Soviet Union in 1991.