| 40351 | April 8 | Event | 1864 – American Civil War: Battle of Mansfield: Union forces are thwarted by the Confederate army at Mansfield, Louisiana. |
| 40352 | April 8 | Event | 1866 – Italy and Prussia ally against the Austrian Empire. |
| 40353 | April 8 | Event | 1886 – William Ewart Gladstone introduces the first Irish Home Rule Bill into the British House of Commons. |
| 40354 | April 8 | Event | 1895 – In Pollock v. Farmers' Loan & Trust Co. the Supreme Court of the United States declares unapportioned income tax to be unconstitutional. |
| 40355 | April 8 | Event | 1904 – The French Third Republic and the United Kingdom of Great Britain and Ireland sign the Entente cordiale. |
| 40356 | April 8 | Event | 1904 – British mystic Aleister Crowley transcribes the first chapter of The Book of the Law. |
| 40357 | April 8 | Event | 1904 – Longacre Square in Midtown Manhattan is renamed Times Square after The New York Times. |
| 40358 | April 8 | Event | 1906 – Auguste Deter, the first person to be diagnosed with Alzheimer's disease, dies. |
| 40359 | April 8 | Event | 1908 – Harvard University votes to establish the Harvard Business School. |
| 40360 | April 8 | Event | 1911 – Dutch physicist Heike Kamerlingh Onnes discovers superconductivity. |
| 40361 | April 8 | Event | 1913 – The 17th Amendment to the United States Constitution, requiring direct election of Senators, becomes law. |
| 40362 | April 8 | Event | 1916 – In Corona, California, race car driver Bob Burman crashes, killing three (including himself), and badly injuring five spectators. |
| 40363 | April 8 | Event | 1918 – World War I: Actors Douglas Fairbanks and Charlie Chaplin sell war bonds on the streets of New York City's financial district. |
| 40364 | April 8 | Event | 1924 – Sharia courts are abolished in Turkey, as part of Atatürk's Reforms. |
| 40365 | April 8 | Event | 1929 – Indian independence movement: At the Delhi Central Assembly, Bhagat Singh and Batukeshwar Dutt throw handouts and bombs to court arrest. |
| 40366 | April 8 | Event | 1935 – The Works Progress Administration is formed when the Emergency Relief Appropriation Act of 1935 becomes law. |
| 40367 | April 8 | Event | 1942 – World War II: Siege of Leningrad: Soviet forces open a much-needed railway link to Leningrad. |
| 40368 | April 8 | Event | 1942 – World War II: The Japanese take Bataan in the Philippines. |
| 40369 | April 8 | Event | 1943 – U.S. President Franklin D. Roosevelt, in an attempt to check inflation, freezes wages and prices, prohibits workers from changing jobs unless the war effort would be aided thereby, and bars rate increases by common carriers and public utilities. |
| 40370 | April 8 | Event | 1945 – World War II: After an air raid accidentally destroys a train carrying about 4,000 Nazi concentration camp internees in Prussian Hanover, the survivors are massacred by Nazis. |
| 40371 | April 8 | Event | 1946 – Électricité de France, the world's largest utility company, is formed as a result of the nationalisation of a number of electricity producers, transporters and distributors. |
| 40372 | April 8 | Event | 1950 – India and Pakistan sign the Liaquat–Nehru Pact. |
| 40373 | April 8 | Event | 1952 – U.S. President Harry Truman calls for the seizure of all domestic steel mills to prevent a nationwide strike. |
| 40374 | April 8 | Event | 1953 – Mau Mau leader Jomo Kenyatta is convicted by Kenya's British rulers. |
| 40375 | April 8 | Event | 1954 – A Royal Canadian Air Force Canadair Harvard collides with a Trans-Canada Airlines Canadair North Star over Moose Jaw, Saskatchewan, killing 37 people. |
| 40376 | April 8 | Event | 1954 – South African Airways Flight 201 A de Havilland DH.106 Comet 1 crashes into the sea during night killing 21 people. |
| 40377 | April 8 | Event | 1959 – A team of computer manufacturers, users, and university people led by Grace Hopper meets to discuss the creation of a new programming language that would be called COBOL. |
| 40378 | April 8 | Event | 1959 – The Organization of American States drafts an agreement to create the Inter-American Development Bank. |
| 40379 | April 8 | Event | 1960 – The Netherlands and West Germany sign an agreement to negotiate the return of German land annexed by the Dutch in return for 280 million German marks as Wiedergutmachung. |
| 40380 | April 8 | Event | 1961 – A large explosion on board the MV Dara in the Persian Gulf kills 238. |