1403

January–December

• January/February - In the Treaty of Gallipoli, Süleyman Çelebi makes wide-ranging concessions to the Byzantine Empire and other Christian powers in the southern Balkans.
• February 7 - King Henry IV of England marries as his second wife Joan of Navarre, the daughter of King Charles II of Navarre and widow of John IV, Duke of Brittany, at Winchester Cathedral.
• March 12 - As King Martin I of Aragon helps to end the siege by the French of the papal palace in Avignon, Antipope Benedict XIII flees to Aragon.
• April - Balša III succeeds his father Đurađ II as ruler of the Principality of Zeta.
• May 21 - Ruy Gonzalez de Clavijo, an ambassador from the king of Castile to Timur, leaves Cadiz; he arrives in Samarkand over a year later.
• Before July 21 - Henry 'Hotspur' Percy forms an alliance with Welsh rebel Owain Glyndŵr.
• July 21 - Battle of Shrewsbury: King Henry IV of England defeats a rebel army led by "Hotspur" Percy, who is killed in the battle.
• October 7 - Battle of Modon: The Genoese fleet under Jean Le Maingre is defeated by the Republic of Venice, at Modon in the Peloponnese.

  Date unknown

• Jan Hus begins preaching Wycliffite ideas in Bohemia.
• In China, the Yongle Emperor of the Ming Dynasty
• * moves the capital from Nanjing to Beijing.
• * commissions the Yongle Encyclopedia, one of the world's earliest and largest known general encyclopedias.
• * orders his coastal provinces to build a vast fleet of ships, with construction centered at Longjiang near Nanjing; the inland provinces are to provide wood and float it down the Yangtze River.
• The Temple of a City God is constructed in Shanghai.
• The Gur-e Amir Mausoleum is built in Samarkand by Timur, after the death of his grandson Muhammad Sultan, and eventually becomes the family mausoleum of the Timurid Dynasty.
• Georgia makes peace with Timur, but has to recognise him as a suzerain and pay him tribute.
• The world's first quarantine station is built in Venice, to protect against the Black Death.
• Grand Duke Vytautas ends his alliance with Muscovy, and captures Vyazma and Smolensk.
• Stefan Lazarević establishes Belgrade, as the capital of the Serbian Despotate.
• A guild of stationers is founded in the City of London. As the Worshipful Company of Stationers and Newspaper Makers, it continues to be a Livery Company in the 21st Century.
• In Ireland
• * Tadgh Ruadh mac Maelsechlainn O Cellaigh succeeds Conchobar an Abaidh mac Maelsechlainn O Cellaigh, as King of Hy-Many, in present-day Galway and Roscommon.
• * Maolmhordha mac Con Connacht succeeds Giolla Iosa mac Pilib, as King of East Breifne, in present-day Leitrim and Cavan.
• probable - Ououso becomes King of Nanzan, in present-day south Okinawa, Japan.