1403

January–March

• January 5 - In what is now Myanmar, peace negotiations begin between King Razadarit of Hanthawaddy at his capital Pegu, with the emissaries of Minkhaung I, ruler of the Kingdom of Ava, 10 days after the Ava forces defeated Razadarit's army at the Battle of Nawin.
• January 23 - The Yongle Era in China begins with the first day of the Chinese New Year, six months after King Zhu Di of the Yan State arrived at Nanjing, deposed the southern Chinese Emperor Zhu Yun Wen, and proclaimed himself as the Emperor Cheng Zu.
• February 20 - Signing of the Treaty of Gallipoli is completed as 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, Queen of England|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 the Crown of Aragon.
• March 13 - Muhammad Sultan Mirza, the favorite grandson and heir to the throne of the Emperor Tamerlane, Emperor of Transoxiana, dies from injuries sustained in the Battle of Ankara.
• March 23 - Stříbrná Skalice in Central Bohemia is razed by Sigismund of Luxembourg.

April–June

• April 1 - Prince Henry of England, son of King Henry IV, is appointed by his father to serve for one year as the Royal Lieutenant of Wales, with command over English toops to fight the Welsh rebels.
• April 3 - Jean II Le Maingre of France, also known as Boucicaut, the French Governor of Genoa, leads a fleet of 18 ships, 600 horses and 700 infantry to stop an attack by Muslims on the island of Cyprus and the city of Famagusta. Boucicaut besieges the Muslim city of Candelore on June 24.
• 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.
• June 9 - The Byzantine Emperor Manuel II Palaiologos returns to Constantinople after an absence for more than two years in Western Europe.
• June 3 - The coronation of Eleanor of Castile, wife of King Carlos III of Navarre, as Queen of Navarre takes place in Pamplona, now in Spain.
• June 14 - The Emperor Manuel II restores Matthew I as the Ecumenical Patriarch of Constantinople, leader of the Eastern Orthodox Christians. Matthew had been deposed the previous autumn during the Emperor's absence from Byzantium.
• June 15 - John III of Soltaniyeh, a Domincan friar of the Roman Catholic Church, arrives in Paris as an emissary of the conqueror Timur, Emir of Transoxiana, in order to secure an agreement with King Charles VI of France in order to open trade relations between the two nations.

July–September

• July 21 - Battle of Shrewsbury: King Henry IV of England defeats a rebel army led by "Hotspur" Percy, who had allied with the Welsh rebel Owain Glyndŵr. Percy is killed in the battle.
• August 5 - The coronation of Ladislaus of Naples as King of Hungary and Croatia takes place in Zara, where Ladislaus had arrived on July 19. His reign lasts less than four months before he is deposed.
• September 4 - The first 200 Chinese treasure ships are ordered by the new Ming dynasty Emperor Cheng Zu from the Capital Guards at Nanjing.

October–December

• October 7 - Battle of Modon: The Genoese fleet under Jean Le Maingre is defeated by the Republic of Venice, at Modon in the Peloponnese.
• October 18 - An English fleet organised by John Hawley of Dartmouth and Thomas Norton of Bristol seizes seven French merchant vessels in the English Channel.
• November 9 - Waleran III, Count of Ligny, a relative in France of the late King Richard II of England, informs King Henry IV of plans to lead an attack on England.
• November - An English revenge raid on Brittany by Sir William Wilford captures 40 ships and causes considerable damage ashore.
• December 12 - Local English forces defeat an attempted French raid on the Isle of Wight under Waleran III, Count of Ligny.
• December 22 - Pope Boniface IX annuls and revokes numerous indulgences previously paid to the Roman Catholic Church in return for a reduction of time in purgatory.

Date unknown

• Jan Hus begins preaching Wycliffite ideas in Bohemia.
• In China, the Emperor Cheng Zu moves the capital from Nanjing to Beijing, commissions the Yongle Encyclopedia, one of the world's earliest and largest known general encyclopedias, and 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, the Lazzaretto Vecchio, 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
• * Tadhg Ruadh mac Maelsechlainn O Cellaigh succeeds Conchobar an Abaidh mac Maelsechlainn O Cellaigh, as King of Hy-Many, in present-day counties Galway and Roscommon.
• * Maolmhordha mac Con Connacht succeeds Giolla Iosa mac Pilib, as King of East Breifne, in present-day counties Leitrim and Cavan.probable - Ououso becomes King of Nanzan, in present-day south Okinawa, Japan.