May 3–Pope Boniface IX of Rome excommunicates Onorato Caetani, Great Constable of the Kingdom of Naples, who had previously been excommunicated in 1367 by Pope Urban V of Rome, and then was forgiven in 1378 by Pope Clement VII of Avignon. Boniface's action follows Caetani's continued support of the Avignon papacy, after which a crusade against Caetani's properties at Fondi.
May 10– The Treaty of Tarbes is signed between representatives of King Charles VI of France and Archambaud of Grailly, who has been an ally of the French monarch's enemy, King Richard II of England. Under the treaty, de Grailly is made Count of Foix in southern France, in return for breaking his alliance with King Richard. Two of the Count of Foix's sons are sent as hostages to the Royal Court of France in order to secure the terms of the agreement.
September 1– Richard II, though still nominally the King of England, is imprisoned by Henry Bolingbroke at the Tower of London.
September 30– King Richard II of England surrenders his crown to Henry Bolingbroke at an assembly of the House of Lords at Westminster Hall in London, where articles of desposition are read to him by the Archbishop of Canterbury. King Richard abdicates, and the Lords proclaim Bolingbroke as King Henry IV.
Sultan Bayezid I of the Ottoman Empire invades Mamluk-occupied Syria. A rift forms between Sultan Bayezid and Timur of the Timurid Empire, who also wanted to conquer Syria.
↑Kekewich, Margaret L. (2008). The Good King: René of Anjou and Fifteenth Century Europe. Palgrave Macmillan. p.51. ISBN978-1-4039-8820-1.
↑Halecki, Oscar (1991). Jadwiga of Anjou and the Rise of East Central Europe. Polish Institute of Arts and Sciences of America. p.257. ISBN0-88033-206-9.
↑Fryde, E. B.; Greenway, D. E.; Porter, S.; Roy, I. (1996). Handbook of British Chronology (Third reviseded.). Cambridge: Cambridge University Press. ISBN0-521-56350-X.
↑Documenta Romaniae Historica A. Moldova, vol. I (1384-1475) Institutul de Istorie și Arheologie A.D. Xenopol, Editura Academiei Republicii Socialiste România, București, 1975) pp. 10-16