| 31411 | March 20 | Holiday and observance | World Sparrow Day (Nature Forever Society) |
| 31412 | March 21 | Event | 537 – Siege of Rome: King Vitiges attempts to assault the northern and eastern city walls, but is repulsed at the Praenestine Gate, known as the Vivarium, by the defenders under the Byzantine generals Bessas and Peranius. |
| 31413 | March 21 | Event | 630 – Emperor Heraclius returns the True Cross, one of the holiest Christian relics, to Jerusalem. |
| 31414 | March 21 | Event | 717 – Battle of Vincy between Charles Martel and Ragenfrid. |
| 31415 | March 21 | Event | 1152 – Annulment of the marriage of King Louis VII of France and Queen Eleanor of Aquitaine. |
| 31416 | March 21 | Event | 1188 – Emperor Antoku accedes to the throne of Japan. |
| 31417 | March 21 | Event | 1413 – Henry V becomes King of England. |
| 31418 | March 21 | Event | 1556 – In Oxford, Archbishop of Canterbury Thomas Cranmer is burned at the stake. |
| 31419 | March 21 | Event | 1788 – A fire in New Orleans leaves most of the town in ruins. |
| 31420 | March 21 | Event | 1800 – With the church leadership driven out of Rome during an armed conflict, Pius VII is crowned Pope in Venice with a temporary papal tiara made of papier-mâché. |
| 31421 | March 21 | Event | 1801 – The Battle of Alexandria is fought between British and French forces near the ruins of Nicopolis in Egypt. |
| 31422 | March 21 | Event | 1804 – Code Napoléon is adopted as French civil law. |
| 31423 | March 21 | Event | 1814 – Napoleonic Wars: Austrian forces repel French troops in the Battle of Arcis-sur-Aube. |
| 31424 | March 21 | Event | 1821 – Greek War of Independence: First revolutionary act in the monastery of Agia Lavra, Kalavryta. |
| 31425 | March 21 | Event | 1844 – The Bahá'í calendar begins. This is the first day of the first year of the Bahá'í calendar. It is annually celebrated by members of the Bahá'í Faith as the Bahá'í New Year or Náw-Rúz. |
| 31426 | March 21 | Event | 1857 – An earthquake in Tokyo, Japan kills over 100,000. |
| 31427 | March 21 | Event | 1861 – Alexander Stephens gives the Cornerstone Speech. |
| 31428 | March 21 | Event | 1871 – Otto von Bismarck is appointed Chancellor of the German Empire. |
| 31429 | March 21 | Event | 1871 – Journalist Henry Morton Stanley begins his trek to find the missionary and explorer David Livingstone. |
| 31430 | March 21 | Event | 1913 – Over 360 are killed and 20,000 homes destroyed in the Great Dayton Flood in Dayton, Ohio. |
| 31431 | March 21 | Event | 1918 – World War I: The first phase of the German Spring Offensive, Operation Michael, begins. |
| 31432 | March 21 | Event | 1919 – The Hungarian Soviet Republic is established becoming the first Communist government to be formed in Europe after the October Revolution in Russia. |
| 31433 | March 21 | Event | 1921 – The New Economic Policy is implemented by the Bolshevik Party in response to the economic failure as a result of war communism. |
| 31434 | March 21 | Event | 1925 – The Butler Act prohibits the teaching of human evolution in Tennessee. |
| 31435 | March 21 | Event | 1925 – Syngman Rhee is removed from office after being impeached as the President of the Provisional Government of the Republic of Korea. |
| 31436 | March 21 | Event | 1928 – Charles Lindbergh is presented with the Medal of Honor for the first solo trans-Atlantic flight. |
| 31437 | March 21 | Event | 1933 – Construction of Dachau, the first Nazi concentration camp, is completed. |
| 31438 | March 21 | Event | 1935 – Shah of Iran Reza Shah Pahlavi formally asks the international community to call Persia by its native name, Iran, meaning "Land of the Aryans". |
| 31439 | March 21 | Event | 1937 – Ponce massacre: Nineteen people in Ponce, Puerto Rico, are gunned down by a police squad acting under orders of US-appointed Governor, Blanton C. Winship. |
| 31440 | March 21 | Event | 1943 – Wehrmacht officer Rudolf von Gersdorff plots to assassinate Adolf Hitler by using a suicide bomb, but the plan falls through. Von Gersdorff is able to defuse the bomb in time and avoid suspicion. |