| 43291 | April 15 | Event | 1927 – The Great Mississippi Flood of 1927, the most destructive river flood in U.S. history, begins. |
| 43292 | April 15 | Event | 1935 – Roerich Pact signed in Washington, D.C. |
| 43293 | April 15 | Event | 1936 – First day of the Arab revolt in Mandatory Palestine. |
| 43294 | April 15 | Event | 1936 – Aer Lingus (Aer Loingeas) is founded by the Irish government as the national airline of the Republic of Ireland. |
| 43295 | April 15 | Event | 1940 – The Allies begin their attack on the Norwegian town of Narvik which is occupied by Nazi Germany. |
| 43296 | April 15 | Event | 1941 – In the Belfast Blitz, two-hundred bombers of the German Luftwaffe attack Belfast, Northern Ireland, United Kingdom killing one thousand people. |
| 43297 | April 15 | Event | 1942 – The George Cross is awarded "to the island fortress of Malta: Its people and defenders" by King George VI. |
| 43298 | April 15 | Event | 1945 – The Bergen-Belsen concentration camp is liberated. |
| 43299 | April 15 | Event | 1947 – Jackie Robinson debuts for the Brooklyn Dodgers, breaking baseball's color line. |
| 43300 | April 15 | Event | 1952 – The maiden flight of the B-52 Stratofortress |
| 43301 | April 15 | Event | 1955 – McDonald's restaurant dates its founding to the opening of a franchised restaurant by Ray Kroc, in Des Plaines, Illinois |
| 43302 | April 15 | Event | 1960 – At Shaw University in Raleigh, North Carolina, Ella Baker leads a conference that results in the creation of the Student Nonviolent Coordinating Committee, one of the principal organizations of the African-American Civil Rights Movement in the 1960 |
| 43303 | April 15 | Event | 1964 – The first Ford Mustang rolls off the show room floor, two days before it is set to go on sale nationwide. |
| 43304 | April 15 | Event | 1969 – The EC-121 shootdown incident: North Korea shoots down a United States Navy aircraft over the Sea of Japan, killing all 31 on board. |
| 43305 | April 15 | Event | 1970 – During the Cambodian Civil War, massacres of the Vietnamese minority results in 800 bodies flowing down the Mekong river into South Vietnam. |
| 43306 | April 15 | Event | 1983 – Tokyo Disneyland opens to the public. |
| 43307 | April 15 | Event | 1984 – The inaugural World Youth Day is held in St. Peter's Square, Vatican City. |
| 43308 | April 15 | Event | 1986 – The United States launches Operation El Dorado Canyon, its bombing raids against Libyan targets in response to a bombing in West Germany that killed two U.S. servicemen. |
| 43309 | April 15 | Event | 1989 – Hillsborough disaster: A human crush occurs at Hillsborough Stadium, home of Sheffield Wednesday, in the FA Cup Semi-final, resulting in the deaths of 96 Liverpool fans. |
| 43310 | April 15 | Event | 1989 – Upon Hu Yaobang's death, the Tiananmen Square protests of 1989 begin in China. |
| 43311 | April 15 | Event | 2013 – Two bombs explode near the finish line at the Boston Marathon in Boston, Massachusetts, killing three people and injuring 264 others. |
| 43312 | April 15 | Event | 2014 – More than 200 female students are declared missing after a mass kidnapping in Borno State, Nigeria. |
| 43313 | April 15 | Birth | 1367 – Henry IV of England (d. 1413) |
| 43314 | April 15 | Birth | 1452 – Leonardo da Vinci, Italian painter, sculptor, and architect (d. 1519) |
| 43315 | April 15 | Birth | 1552 – Pietro Cataldi, Italian mathematician and astronomer (d. 1626) |
| 43316 | April 15 | Birth | 1588 – Claudius Salmasius, French author and scholar (d. 1653) |
| 43317 | April 15 | Birth | 1641 – Robert Sibbald, Scottish physician and geographer (d. 1722) |
| 43318 | April 15 | Birth | 1642 – Suleiman II, Ottoman sultan (d. 1691) |
| 43319 | April 15 | Birth | 1646 – Christian V of Denmark (d. 1699) |
| 43320 | April 15 | Birth | 1646 – Pierre Poiret, French mystic and philosopher (d. 1719) |