1440

January–December

• February 21 – The Prussian Confederation is formed.
• April 9 – Christopher of Bavaria is elected King of Denmark.
• April – Murad II lays siege to Belgrade. The city is heavily damaged, but the defenders' use of artillery prevents the Turks from capturing the city.
• September 13 – Gilles de Rais is taken into custody, upon an accusation brought against him by the Bishop of Nantes.
• September – The term of Regent of Sweden Karl Knutsson Bonde ends, as newly elected king of Denmark Christopher of Bavaria is also elected king of Sweden.
• October 22 – Breton knight Gilles de Rais confesses, and is sentenced to death.

  Date unknown

• Itzcóatl, Aztec ruler of Tenochtitlan, dies and is succeeded by Moctezuma I .
• Lorenzo Valla's De falso credita et ementita Constantini Donatione declamatio demonstrates that the Donation of Constantine is a forgery.
• Eton College is founded by Henry VI of England.
• Sir Richard Molyneux is appointed constable of Liverpool Castle, in England.
• The Ming Dynasty government of China begins a decade-long series of issuing harsh edicts towards those who illegally mine silver, the latter known as 'miner bandits', a trend begun in 1438. The government wants to cap the amount of silver circulating into the market, as more grain taxes are converted into silver taxes. The government establishes community night watches known as 'watches and tithings', who ensure that illegal mining activities are brought to a halt. However, these are desperate measures, as illegal silver mining continues to thrive as a dangerous but lucrative venture.
• Zhu Quan writes the Cha Pu in China.