Charles I of Hungary in the context of "Charles II of Naples"

The Visegrád Group (also known as the Visegrád Four or the V4) is a cultural and political alliance of four Central European countries: the Czech Republic, Hungary, Poland, and Slovakia. The alliance aims to advance co-operation in military, economic, cultural and energy affairs. All four nations are also members of the European Union, the North Atlantic Treaty Organization, and the Three Seas Initiative.

The alliance traces its origins to the summit meetings of leaders of Czechoslovakia, Hungary and Poland, held in the Hungarian castle town of Visegrád on 15 February 1991. Visegrád was chosen as the location for the summits as an intentional allusion to the medieval Congress of Visegrád between John I of Bohemia, Charles I of Hungary, and Casimir III of Poland in 1335.

Louis I, also known as Louis the Great (Hungarian: Nagy Lajos; Croatian: Ludovik Veliki; Slovak: Ľudovít Veľký) or Louis the Hungarian (Polish: Ludwik Węgierski; 5 March 1326 – 10 September 1382), was King of Hungary and Croatia from 1342 and King of Poland from 1370 until his death in 1382. He was the first child of Charles I of Hungary and his wife, Elizabeth of Poland, to survive infancy. A 1338 treaty between his father and Casimir III of Poland, Louis's maternal uncle, confirmed Louis's right to inherit the Kingdom of Poland if his uncle died without a son. In exchange, Louis was obliged to assist his uncle to reoccupy the lands that Poland had lost in previous decades. He bore the title Duke of Transylvania between 1339 and 1342 but did not administer the province.

Louis was of age when he succeeded his father in 1342, but his deeply religious mother exerted a powerful influence on him. He inherited a centralized kingdom and a rich treasury from his father. During the first years of his reign, Louis launched a crusade against the Lithuanians and restored royal power in Croatia; his troops defeated a Tatar army, expanding his authority towards the Black Sea. When his brother, Andrew, Duke of Calabria, husband of Queen Joanna I of Naples, was assassinated in 1345, Louis accused the queen of his murder and punishing her became the principal goal of his foreign policy. He launched two campaigns to the Kingdom of Naples between 1347 and 1350. His troops occupied large territories on both occasions, and Louis adopted the styles of Neapolitan sovereigns (including the title of King of Sicily and Jerusalem), but the Holy See never recognized his claim. Louis's arbitrary acts and atrocities committed by his mercenaries made his rule unpopular in Southern Italy. He withdrew all his troops from the Kingdom of Naples in 1351.

Wenceslaus III (Czech: Václav III, Hungarian: Vencel, Polish: Wacław, Croatian: Vjenceslav, Slovak: Václav; 6 October 1289 – 4 August 1306) was King of Hungary and Croatia from 1301 to 1305, and King of Bohemia and Poland from 1305. He was the son of Wenceslaus II, King of Bohemia (later also crowned King of Poland), and Judith of Habsburg.

While still a child, Wenceslaus was betrothed to Elizabeth, the only daughter of Andrew III of Hungary. After Andrew's death in early 1301, most Hungarian lords and prelates elected Wenceslaus as king, although Pope Boniface VIII supported a rival claimant, Charles Robert of the royal House of Anjou (Kingdom of Naples).

In the Late Middle Ages, the Kingdom of Hungary, a country in Central Europe, experienced a period of interregnum in the early 14th century. Royal power was restored under Charles I (1308–1342), a scion of the Capetian House of Anjou. Gold and silver mines opened in his reign produced about one third of the world's total production up until the 1490s. The kingdom reached the peak of its power under Louis the Great (1342–1382) who led military campaigns against Lithuania, southern Italy and other faraway territories.

The expansion of the Ottoman Empire reached the kingdom under Sigismund of Luxembourg (1387–1437). In the next decades, a talented military commander, John Hunyadi, directed the fight against the Ottomans. His victory at Nándorfehérvár (present-day Belgrade, Serbia) in 1456 stabilized the southern frontiers for more than half a century. The first king of Hungary without dynastic ancestry was Matthias Corvinus (1458–1490), who led several successful military campaigns and also became the King of Bohemia and the Duke of Austria. With his patronage Hungary became the first country which adopted the Renaissance from Italy.

Joanna I, also known as Johanna I (Italian: Giovanna I; December 1325 – 27 July 1382), was Queen of Naples, and Countess of Provence and Forcalquier from 1343 to 1381; she was also Princess of Achaea from 1373 to 1381.

Joanna was the eldest daughter of Charles, Duke of Calabria and Marie of Valois to survive infancy. Her father was the son of Robert the Wise, King of Naples, but he died before his father in 1328. Three years later, King Robert appointed Joanna as his heir and ordered his vassals to swear fealty to her. To strengthen Joanna's position, he concluded an agreement with his nephew, King Charles I of Hungary, about the marriage of Charles's younger son, Andrew, and Joanna. Charles I also wanted to secure his uncle's inheritance to Andrew, but King Robert named Joanna as his sole heir on his deathbed in 1343. He also appointed a regency council to govern his realms until Joanna's 21st birthday, but the regents could not actually take control of state administration after the King's death.

John Alexander Basarab I (Romanian: [basaˈrab] ), also known as Basarab the Founder (Romanian: Basarab Întemeietorul; c. 1270 – 1351/1352), was a voivode and later the first independent ruler of Wallachia who lived in the first half of the 14th century. Many details of his life are uncertain. According to two popular theories, Basarab either came into power between 1304 and 1324 by dethroning or peacefully succeeding the legendary founder of Wallachia, Radu Negru, or in 1310 by succeeding his father, Thocomerius.

A royal charter issued on 26 July 1324 is the first document to reference Basarab. According to the charter, he was subject to Charles I of Hungary as the voivode of Wallachia. Basarab became "disloyal to the Holy Crown of Hungary" in 1325. He seized the Banate of Severin and raided the southern regions of the Kingdom of Hungary. Basarab supported Michael Shishman of Bulgaria's attack against the Kingdom of Serbia, but their united armies were defeated in the Battle of Velbazhd on 28 July 1330. Soon after, Charles I of Hungary invaded Wallachia, but the Wallachians ambushed the royal troops in the Battle of Posada, between the 9 and 12 November 1330, nearly annihilating the entire force, subsequently ending Hungarian suzerainty in Wallachia, allowing the foundation of the first independent Romanian principality. Basarab's descendants ruled Wallachia for at least two centuries. The region of Bessarabia, situated between the rivers Dniester and Prut, was named for the Basarab dynasty.

The Battle of Posada (9–12 November 1330) was fought between Basarab I of Wallachia and Charles I of Hungary (also known as Charles Robert).The small Wallachian army led by Basarab, formed of cavalry and foot archers, as well as local peasants, managed to ambush and defeat the 30,000-strong Hungarian army, in a mountainous region.

The battle resulted in a major Wallachian victory. Sălăgean writes that the victory "sanctioned the independence of Wallachia from the Hungarian crown" and altered its international status. Georgescu describes Wallachia as the "first independent Romanian principality." Although kings of Hungary continued to demand loyalty from the voivodes of Wallachia, Basarab and his successors yielded to them only temporarily in the 14th century.

The first Congress of Visegrád was a 1335 summit in Visegrád in which Kings John I of Bohemia, Charles I of Hungary and Croatia, and Casimir III of Poland formed an anti-Habsburg alliance. The three leaders agreed to create new commercial routes to bypass the staple port of Vienna, which made merchants offer their goods there before they could try elsewhere, and to obtain easier access to other European markets.

The summit was triggered by the sudden expansion of Habsburg power in the region, which had taken over Carinthia and Carniola after the death of duke Henry of Gorizia-Tyrol, who had unsuccessfully claimed the Bohemian and the Polish crowns.

Elizabeth of Poland (Hungarian: Erzsébet, Polish: Elżbieta; 1305 – 29 December 1380) was Queen of Hungary by marriage to Charles I of Hungary, and regent of Poland from 1370 to 1376 during the reign of her son Louis I.