Editing 1440 (section)

=== April–June ===
* [[April 9]] &ndash; [[Christopher of Bavaria]] is elected [[King of Denmark]].
* [[April]] &ndash; Ottoman Sultan [[Murad II]] begins the [[Siege of Belgrade (1440)|siege]] of [[Belgrade]], at the time part of the [[Kingdom of Hungary]] after the conquest of Serbia. The fortress is heavily damaged, but the defenders' use of [[artillery]] prevents the [[Ottoman Empire|Turks]] from capturing the city, and the siege ends after six months.
* [[May 4]] &ndash; [[Metrophanes II of Constantinople|Metrophanes II]], Bishop of Cyzicus, is appointed by the Byzantine Emperor [[John VIII Palaiologos]] as the new [[List of ecumenical patriarchs of Constantinople|Ecumenical Patriarch of Constantinople]], leader of the Eastern Orthodox Church, to succeed the late [[Joseph II of Constantinople|Joseph II]], who had died in 1439.
* [[May 15]] &ndash; [[Elizabeth of Luxembourg]], regent for the vacant throne of Hungary, has her infant son, [[Ladislaus the Posthumous]], crowned king at [[Székesfehérvár]] with the stolen [[Holy Crown of Hungary|Crown of Saint Stephen]].
* [[June 29]] &ndash; 
**The League of Italian States (Florence, Venice and the Papal States) defeats the army of the [[Duchy of Milan]] at the [[Battle of Anghiari]] in [[Tuscany]].<ref>{{Cite web |url=http://www.anghiari.it/new-english/english/battaglia_anghiari.asp |title=The Battle of Anghiari |access-date=6 February 2014 |archive-url=https://web.archive.org/web/20140103180717/http://www.anghiari.it/new-english/english/battaglia_anghiari.asp |archive-date=3 January 2014 |url-status=dead}}</ref>
**[[Casimir IV Jagiellon]] is proclaimed as the new [[List of Lithuanian monarchs|Grand Duke of Lithuania]] by the [[Lithuanian Council of Lords]].<ref>J. Kiaupienė, ''Valdžios krizės pabaiga ir Kazimieras Jogailaitis'' (The End of the Government Crisis and Kazimieras Jogailaitis), (Vilnius: Electronic Publishing House, 2003)</ref>
**The [[Diet of Hungary]] approves a resolution declaring the coronation of Ladislaus as King of Hungary to be invalid, declaring that "the crowning of kings is always dependent on the will of the kingdom's inhabitants, in whose consent both the effectiveness and the force of the crown reside".<ref>{{cite book |last=Engel |first=Pál |year=2001 |title=The Realm of St Stephen: A History of Medieval Hungary, 895–1526 |publisher= I.B. Tauris Publishers |isbn=1-86064-061-3}}</ref>