In the year AD
- The Hussite Wars continue between the Holy Roman Empire and the Bohemian followers of Jan Hus. Following the failed first crusade against the Hussites in 1420, the German princes undertake a second crusade, laying siege to the town of Zatec but failing to take it when Holy Roman Emperor Sigismund and his troops are detained by an Ottoman incursion in Hungary. Meanwhile an assembly of Hussites votes to depose Sigsimund as king of Bohemia, and elects Witowt of Lithuania as antiking. Sigismund finally arrives in Bohemia in the end of the year and recaptures the mint town of Kutná Hora, but is ousted within weeks by Jan Zizka early the following year.
- The Hundred Years War drags on. In the Battle of Baugé, a small force of French and Scottish troops under Charles the Dauphin surprises and defeats a larger English force commanded Henry V's brother Thomas, Duke of Clarence, who is killed in the fighting. The French receive a setback, however, at the hands of England's Burgundian allies at the Battle of Mons-en-Vimeu. Meanwhile, Henry lays siege to Meaux.
- King Alfonso V of Aragon defeats Louis III of Anjou to secure the throne of Naples for Joanna II, who rewards him by making him her heir.
- Duke of Milan Filippo Maria Visconti forcibly annexes Genoa.
- Unusually high tides cause the St. Elizabeth Flood near Dordrecht in the Netherlands, drowning 72 villages and killing a reported 10,000 people.
- Ming emperor Chengzu relocates his capital from Nanjing to Beijing.
- A sixth Chinese treasure fleet under the command of Admiral Zheng He visits Southeast Asia, India, Arabia, and Africa, reaching as far as Zanzibar. According to amateur historian Gavin Menzies' book 1421: The Year China Discovered America, the ships then traveled onward around Africa to North America and circumnavigated the globe, although these claims are disputed by virtually all other scholars.
These people were born in 1421:
These people died in 1421:
1420 - 1421 - 1422