Władysław II Jagiełło in the context of "Łódź"

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.

Poland was ruled at various times either by dukes and princes (10th to 14th centuries) or by kings (11th to 18th centuries). During the latter period, a tradition of free election of monarchs made it a uniquely electable position in Europe (16th to 18th centuries).

The first Polish ruler whose existence is not debatable was Duke Mieszko I, who adopted Christianity under the authority of Rome in the year 966. He was succeeded by his son, Bolesław I the Brave, who greatly expanded the boundaries of the Polish state and ruled as the first king in 1025. The following centuries gave rise to the mighty Piast dynasty, consisting of both kings such as Mieszko II Lambert, Przemysł II or Władysław I the Elbow-high and dukes like Bolesław III Wrymouth. The dynasty's rule over Poland ceased with the death of Casimir III the Great in 1370. In the same year, the Capetian House of Anjou became the ruling house with Louis I as king of both Poland and Hungary. His daughter, Jadwiga, later married Jogaila, the pagan Grand Duke of Lithuania, who in 1386 was baptized and crowned as Władysław II Jagiełło, thus creating the Jagiellonian dynasty and a personal union between Poland and Lithuania.

Władysław III of Poland (31 October 1424 – presumably 10 November 1444), also known as Ladislaus of Varna, was King of Poland and Supreme Duke of the Grand Duchy of Lithuania from 1434, as well as King of Hungary and Croatia as Vladislaus I from 1440 until his presumed death at the Battle of Varna. He was the eldest son of Władysław II Jagiełło (Jogaila) and the Lithuanian noblewoman Sophia of Halshany.

Władysław succeeded his father shortly before turning ten in 1434 and was, therefore, deemed unfit to rule until coming of age. Cardinal Zbigniew Oleśnicki acted as regent and a temporary provisores council executed power in the king's name. However, Władysław's legitimacy to the crown was contested by Lesser Polish nobles favouring the candidacy of Siemowit V of Masovia, who was of Piast lineage. In the aftermath of the coronation, Spytko III of Melsztyn accused Oleśnicki, the council and the Catholic Church of exploiting the king's youth to hold authority. A sympathiser with the Czech Hussites, Spytko was killed at the Battle of Grotniki in 1439, thus ending the hostilities.

Vytautas the Great (/vɪˈtaʊtəs/; c. 1350 – 27 October 1430) was a ruler of the Grand Duchy of Lithuania. He was also the prince of Grodno (1370–1382), prince of Lutsk (1387–1389), and the postulated king of the Hussites.

In modern Lithuania, Vytautas is revered as a national hero and was an important figure in the national rebirth in the 19th century. Vytautas is a popular male given name in Lithuania. In commemoration of the 500-year anniversary of his death, Vytautas Magnus University was named after him. Monuments in his honour were built in many towns in independent Lithuania during the interwar period from 1918 to 1939. Vytautas knew and spoke the Lithuanian language with his cousin Jogaila.