| 42391 | April 12 | Holiday and observance | Halifax Day (North Carolina) |
| 42392 | April 12 | Holiday and observance | National Redemption Day (Liberia) |
| 42393 | April 13 | Event | 1111 – Henry V is crowned Holy Roman Emperor. |
| 42394 | April 13 | Event | 1204 – Constantinople falls to the Crusaders of the Fourth Crusade, temporarily ending the Byzantine Empire. |
| 42395 | April 13 | Event | 1598 – Henry IV of France issues the Edict of Nantes, allowing freedom of religion to the Huguenots. |
| 42396 | April 13 | Event | 1612 – Miyamoto Musashi defeats Sasaki Kojirō at Funajima island. |
| 42397 | April 13 | Event | 1613 – Samuel Argall captures Native American princess Pocahontas in Passapatanzy, Virginia to ransom her for some English prisoners held by her father. She is brought to Henricus as hostage. |
| 42398 | April 13 | Event | 1699 – Guru Gobind Singh, the Tenth Sikh Guru, Created Khalsa on this day at Anandpur Sahib, Punjab. |
| 42399 | April 13 | Event | 1742 – George Frideric Handel's oratorio Messiah makes its world-premiere in Dublin, Ireland. |
| 42400 | April 13 | Event | 1777 – American Revolutionary War: American forces are ambushed and defeated in the Battle of Bound Brook, New Jersey. |
| 42401 | April 13 | Event | 1829 – The Roman Catholic Relief Act 1829 gives Roman Catholics in the United Kingdom the right to vote and to sit in Parliament. |
| 42402 | April 13 | Event | 1849 – Hungary becomes a republic. |
| 42403 | April 13 | Event | 1861 – American Civil War: Fort Sumter surrenders to Confederate forces. |
| 42404 | April 13 | Event | 1865 – American Civil War: Raleigh, North Carolina is occupied by Union Forces. |
| 42405 | April 13 | Event | 1870 – The New York City Metropolitan Museum of Art is founded. |
| 42406 | April 13 | Event | 1873 – The Colfax massacre, in which more than 60 African Americans are murdered, takes place. |
| 42407 | April 13 | Event | 1902 – James C. Penney opens his first store in Kemmerer, Wyoming. |
| 42408 | April 13 | Event | 1909 – The Turkish military reverses the Ottoman countercoup of 1909 to force the overthrow of Sultan Abdul Hamid II. |
| 42409 | April 13 | Event | 1919 – The establishment of the Provisional Government of the Republic of Korea. |
| 42410 | April 13 | Event | 1919 – Jallianwala Bagh massacre: British troops gun down at least 379 unarmed demonstrators in Amritsar, India at least 1200 are wounded. |
| 42411 | April 13 | Event | 1919 – Eugene V. Debs is imprisoned at the Atlanta Federal Penitentiary in Atlanta, Georgia, for speaking out against the draft during World War I. |
| 42412 | April 13 | Event | 1941 – A Pact of neutrality between the USSR and Japan is signed. |
| 42413 | April 13 | Event | 1943 – World War II: The discovery of mass graves of Polish prisoners of war killed by Soviet forces in the Katyń Forest Massacre is announced, causing a diplomatic rift between the Polish government-in-exile in London from the Soviet Union, which denies |
| 42414 | April 13 | Event | 1943 – The Jefferson Memorial is dedicated in Washington, D.C., on the 200th anniversary of President Thomas Jefferson's birth. |
| 42415 | April 13 | Event | 1944 – Diplomatic relations between New Zealand and the Soviet Union are established. |
| 42416 | April 13 | Event | 1945 – World War II: German troops kill more than 1,000 political and military prisoners in Gardelegen, Germany. |
| 42417 | April 13 | Event | 1945 – World War II: Soviet and Bulgarian forces capture Vienna, Austria. |
| 42418 | April 13 | Event | 1948 – The Hadassah medical convoy massacre: In an ambush, 79 Jewish doctors, nurses and medical students from Hadassah Hospital and a British soldier are massacred by Arabs in Sheikh Jarra near Jerusalem. |
| 42419 | April 13 | Event | 1953 – CIA director Allen Dulles launches the mind-control program Project MKUltra. |
| 42420 | April 13 | Event | 1958 – Cold War: American Van Cliburn wins the inaugural International Tchaikovsky Competition in Moscow. |