Crown of Poland in the context of "Ladislaus the Short"

Prussia (/ˈprʌʃə/; German: Preußen [ˈpʁɔʏsn̩] ; Old Prussian: Prūsija) was a German state centred on the North European Plain that originated from the 1525 secularization act of the Prussian part of the State of the Teutonic Order. For centuries, the House of Hohenzollern ruled Prussia, expanding its size with the Prussian Army. Prussia, with its capital at Königsberg and then, when it became the Kingdom of Prussia in 1701, Berlin, decisively shaped the history of Germany. Prussia formed the German Empire when it united the German states in 1871. It was de facto dissolved by an emergency decree transferring powers of the Prussian government to German Chancellor Franz von Papen in 1932 and de jure by an Allied decree in 1947.

The name Prussia derives from the Old Prussians who were conquered by the Teutonic Knights – an organized Catholic medieval military order of German crusaders – in the 13th century. In 1308, the Teutonic Knights conquered the region of Pomerelia with Danzig. Their monastic state was mostly Germanised through immigration from central and western Germany, and, in the south, it was Polonised by settlers from Masovia. The imposed Second Peace of Thorn (1466) split Prussia into the western Royal Prussia, a province of Poland, and the eastern Duchy of Prussia, a feudal fief of the Crown of Poland until 1657. After 1525, the Teutonic Order relocated their headquarters to Mergentheim, but managed to keep land in Livonia until 1561. The union of Brandenburg and the Duchy of Prussia in 1618 led to the proclamation of the Kingdom of Prussia in 1701.

Registered Cossacks (Ukrainian: Реєстрові козаки, romanized: Reiestrovi kozaky; Polish: Kozacy rejestrowi) comprised special Cossack units of the Polish–Lithuanian Commonwealth army in the 16th and 17th centuries.

Registered Cossacks became a military formation of the Commonwealth army beginning in 1572 soon after the Union of Lublin (1569), when most of the territory of modern Ukraine passed to the Crown of Poland. Registered Cossack formations were based on the Zaporozhian Cossacks who already lived on the lower reaches of the Dnieper River amidst the Pontic steppes as well as on self-defense formations within settlements in the region of modern Central and Southern Ukraine.

Królewicz (Polish: [kruˈlɛ.vit͡ʂ] , f. królewna [kruˈlɛv.na] ; plural forms królewicze and królewny) was the title given to the sons and daughters of the king of Poland (and Grand Duke of Lithuania at the same time), later the Polish–Lithuanian Commonwealth. It was similar in its distinctiveness to the Spanish and Portuguese title of infante, also reserved to the children of the monarch. Though, it was used only to denote one's status as a King's child. Królewicz and królewna has no direct equivalent in other languages and was translated to the English prince and German Prinz, like dynasts of a royal house. Królewicze since the 16th century could not also be regarded as and equivalent to the princes of the blood, because the Polish monarchy was not hereditary since 1573, when after the death of the last Jagiellon king, future Henry III of France was elected. In official Latin titulature children of Polish kings were often styled as Poloniae princeps or princeps Poloniae, meaning Prince/ss of Poland or Polish prince/ss. In more official way, the full style of sons of monarchs was Dei Gratia regius princeps Poloniae et Lithuaniae for the sons.

Magdeburg rights (German: Magdeburger Recht, Polish: Prawo magdeburskie, Lithuanian: Magdeburgo teisė; also called Magdeburg law) were a set of town privileges first developed by Otto I, Holy Roman Emperor (936–973), which regulated the degree of internal autonomy within cities and villages granted by the local ruler. Named after the city of Magdeburg and based on Roman municipal and universal merchant traditions, these town charters were perhaps the most important set of medieval laws in Central Europe. They became the basis for the German town laws developed during many centuries in the Holy Roman Empire. The Magdeburg rights were adopted and adapted by numerous monarchs, including the rulers of Bohemia, Hungary, Poland, and Lithuania, a milestone in the urbanization of the region which prompted the development of thousands of villages and cities.