Congress of Visegrád (1335) in the context of "Charles I of Hungary"

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.

The Treaty of Trentschin was concluded on 24 August 1335 between King Casimir III of Poland and King John of Bohemia together with his son Margrave Charles IV. The agreement was reached by the agency of Casimir's brother-in-law King Charles I of Hungary and signed at Trentschin Castle in the Kingdom of Hungary (present-day Trenčín, Slovakia). It initiated the transfer of suzerainty over the former Polish province of Silesia to the Kingdom of Bohemia, whereafter the Duchies of Silesia were incorporated into the Bohemian Crown and thus became part of the Holy Roman Empire. Following the integration of this treaty, the three kingdoms of Bohemia, Hungary, and Poland met at the First Congress of Visegrad later in 1335 to further discuss the division of land. This congress also made the treaty official.