First Congress of Vienna
The First Congress of Vienna was held in 1515, attended by the Holy Roman Emperor, Maximilian I, and the Jagiellonian brothers, Vladislaus II, King of Hungary and King of Bohemia, and Sigismund I, King of Poland and Grand Duke of Lithuania. Previously, Vladislaus and Maximilian had agreed on a Habsburg-Jagiellon mutual-succession treaty in 1506.