| 31 March 1000 | Poland [political events] | Boleslaw Chrobry (the Brave) convinces the Emperor Otto III to create the archbishopric of Gniezno for Poland, with Silesia and Pomerania subject to it. Poland is consequently recognized as independent both politically and ecclesiastically. |
| 31 March 1078 | Byzantine Empire [administration] | After a revolt in Constantinople (modern Istanbul, Turkey), the Byzantine emperor Michael VII abdicates and is succeeded by the general Nicephorus III Botaneiates, who has already been proclaimed emperor by the rebels. |
| 31 March 1327 | France [treaties] | Under the Treaty of Paris, King Charles IV of France and King Edward III of England end the ‘war of Saint-Sardos’ and restore Gascony to English rule. |
| 31 March 1492 | Spain, North Africa [legislation] | King Ferdinand V and Queen Isabella I of Aragon and Castile issue an edict that gives Spanish Jews the choice of converting to Christianity within three months or emigrating. 170,000 subsequently choose the latter, many seeking refuge in the Maghreb in North Africa. |
| 31 March 1495 | Italy, Papal States, Spain, Ottoman Empire, France [treaties] | Pope Alexander VI forms the League of Venice with the Holy Roman Empire, Spain, Venice, and Milan, ostensibly to fight the Ottoman Turks, but actually aimed at expelling King Charles VIII of France from Italy. |
| 31 March 1547 | France, Scotland [political events] | Following the death of King Francis I of France, he is succeeded by his son Henry II, an outspoken Catholic. Henry is dominated by Francis, duke of Guise, and by his mistress Diane of Poitiers. Guise negotiates the marriage of the dauphin Francis to Mary Queen of Scots. |
| 31 March 1596 | France [births and deaths] | René Descartes, French philosopher, scientist, and mathematician, considered to be the founder of modern philosophy, whose best-known work is Discours de la méthode/Discourse on Method (1637), born in La Haye, Touraine, France (–1650). |
| 31 March 1621 | Spain [political events] | Philip IV becomes king of Spain on the death of Philip III. He appoints Gaspar de Guzmán, Conde-Duque of Olivares and nephew of Baltazar Zuñiga, former envoy of Prague, as his chief minister. |
| 31 March 1631 | England [births and deaths] | John Donne, the best-known English poet of the metaphysical school, dies in London, England (59). |
| 31 March 1644 | Papal States, Venice, Parma, Italy, Tuscany [treaties] | The Peace of Ferrara is signed in Venice by Pope Urban VIII and the Duke of Parma and his allies, Venice, Modena, and Tuscany. The treaty ends the war of Castro, ongoing since 1642. |
| 31 March 1732 | Austria [births and deaths] | Franz Joseph Haydn, Austrian classical composer, born in Rohrau, Austria (–1809). |
| 31 March 1774 | America, UK [legislation] | In the Boston Port Act, the British Parliament responds to the Boston Tea Party by closing the port of Boston. Americans regard this as the first of the so-called Intolerable Acts. |
| 31 March 1829 | Italy [Catholicism] | After the death of Pope Leo XII on 10 February, the Italian clergyman Francesco Saverio Castiglioni is elected Pope Pius VIII. He is pope until 1830. |
| 31 March 1837 | England [births and deaths] | John Constable, English landscape painter, dies in London, England (59). |
| 31 March 1854 | USA, Japan [trade] | The USA makes its first trade treaty with Japan, negotiated by Commodore Matthew Perry, whose naval mission in 1853 had forced Japan to establish preliminary diplomatic links with the outside world. |
| 31 March 1855 | England [births and deaths] | Charlotte Brontë, English novelist who wrote Jane Eyre (1847), dies in Haworth, Yorkshire (now West Yorkshire), England (38). |
| 31 March 1862 | Ireland [births and deaths] | Arthur Griffith, Irish journalist and nationalist, founder of Sinn Fein (1905) and president of the Irish Republic (1922), born in Dublin, Ireland (–1922). |
| 31 March 1883 | UK [football] | Blackburn Olympic defeat the Old Etonians 2–1 at The Oval, London, England, before a crowd of 8,000 people, to become the first team from the north of England to win the Football Association (FA) Cup. |
| 31 March 1905 | Morocco, Germany, France [diplomacy] | The visit of Emperor Wilhelm II of Germany to Tangier, Morocco, sets off the ‘First Moroccan Crisis’, being seen as a test of the British–French convention of 1904 which arranged for French predominance in Morocco. |
| 31 March 1939 | UK, France, Poland [diplomacy] | Britain and France pledge to support Poland in any attack on Polish independence. On 6 April a pact is signed by all three governments confirming the pledge. |
| 31 March 1971 | USA, South Vietnam [crime and punishment] | The US lieutenant William Calley is sentenced to life imprisonment for the My Lai massacre of 109 civilians in South Vietnam by US troops in March 1968. On 20 August 1971 Lieutenant Calley's prison term is reduced to 20 years. |
| 31 March 1980 | USA [births and deaths] | Jesse Owens, black US track and field athlete who won four gold medals at the 1936 Olympics in Berlin, dies in Phoenix, Arizona (66). |
| 31 March 1984 | India [law and government] | The Indian government agrees to amend the Punjabi constitution to acknowledge Sikhism as a religion distinct from Hinduism. |
| 31 March 1991 | USSR [political events] | The military structure of the Warsaw Pact (formed in 1955 between the USSR and East European communist states) is formally dissolved. |
| 31 March 1997 | USA [terrorism] | The trial of Timothy McVeigh, charged with the Oklahoma City bombing of 19 April 1995, opens in Denver, Colorado; on 2 June, McVeigh is found guilty and on 13 June he is sentenced to death. |
