Year 1420 (MCDXX) was a leap year starting on Monday (link will display the full calendar) of the Julian calendar. Events January–December March – The Çelebi Sultan Mehmed Mosque in Didymoteicho is inaugurated. May 21 – Treaty of Troyes: With the Burgundian faction dominant in France, King Charles VI of France acknowledges Henry V of England as his heir, and as virtual ruler of most of France. May 25 – Henry the Navigator is appointed governor of the Portuguese Order of Christ. June 2 – Catherine of Valois marries King Henry V of England. June 7 – Troops of the Republic of Venice capture Udine after a long siege, ending the independence of the Patriarchal State of Friuli, run by the Patriarch of Aquileia. August 7 – Construction of the dome of Florence Cathedral is started, after Filippo Brunelleschi wins the commission for his "double shell" design. September 1 – a 9.4 MS-strong earthquake shakes Chile's Atacama Region causing tsunamis in Chile as well as Hawaii and Japan.Manuel Abad, Tatiana Izquierdo, Miguel Cáceres, Enrique Bernárdez and Joaquín Rodríguez-Vidal (2018). Coastal boulder deposit as evidence of an ocean-wide prehistoric tsunami originated on the Atacama Desert coast (northern Chile). Sedimentology. Publication: december, 13th, 2018. https://doi.org/10.1111/sed.12570 October 22 – Ghiyāth al-dīn Naqqāsh, an envoy of the embassy sent by the Timurid ruler of Persia, Mirza Shahrukh (r. 1404–1447), to the Ming Dynasty of China during the reign of the Yongle Emperor (r. 1402–1424), records his sight and travel over a large floating pontoon bridge at Lanzhou (constructed earlier in 1372) as he crosses the Yellow River on this day. He writes that it was: "...composed of twenty three boats, of great excellence and strength attached together by a long chain of iron as thick as a man's thigh, and this was moored on each side to an iron post as thick as a man's waist extending a distance of ten cubits on the land and planted firmly in the ground, the boats being fastened to this chain by means of big hooks. There were placed big wooden planks over the boats so firmly and evenly that all the animals were made to pass over it without difficulty." October 28 – Beijing is officially designated the capital of the Ming Dynasty, during the same year that the Forbidden City, the seat of government, is completed. November 1 – Hussite Wars – Battle of Vyšehrad: