Congress of Visegrád (1339)
The second Congress of Visegrád was a 1339 summit in Visegrád that decided that if Casimir III of Poland died without a son, the King of Poland would be the son of Charles I of Hungary.
When Casimir died in 1370 from an injury received while he was hunting, in accordance with the decision of the Congress, Louis I of Hungary, son of Charles I, succeeded him as king of Poland in personal union with Hungary.