Ulrich II, Count of Celje, last ruler of the County of Cilli, is assassinated in Belgrade.
Ulrich II, or Ulrich of Celje (Slovene: Ulrik Celjski / Urh Celjski; Hungarian: Cillei Ulrik; German: Ulrich II von Cilli; 16 February 1406 – 9 November 1456), was the last Princely Count of Celje. At the time of his death, he was captain general and de facto regent of Hungary, ban (governor) of Slavonia, Croatia and Dalmatia and feudal lord of vast areas in present-day Slovenia, Croatia, Bosnia, Austria, and Slovakia. He was also a claimant to the Bosnian throne. He was killed by agents of the Hunyadi clan under unknown circumstances, which plunged Hungary into civil unrest that was resolved a year later by the sudden death of king Ladislas the Posthumous and the election of Matthias Corvinus, the son of John Hunyadi and Ulrich's son-in-law, as king. Ulrich's possessions in the Holy Roman Empire were inherited by the Habsburg Emperor Frederick III, while his possessions in Hungary were reverted to the crown.