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Dr. Martin Luther King Jr. composes his famous "Open Letter from Birmingham Jail" on April 16, 1963, advocating for civil rights. More
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What Happened in April?
Sieges, raids, and monumental deaths. Discover key historical events from April that influenced the world. Dates for earlier events may be approximate.
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The Ford Mustang officially debuted at the New York World's Fair on April 17, 1964, becoming an instant attraction. More than 22,000 mustangs were sold on the first day and over 400,000 sold in the first year.
President Lyndon B. Johnson sends more than 22,000 U.S. troops to the Dominican Republic, on April 28, 1965, purportedly to prevent the establishment of a Communist government in the Central American Nation. The U.S, military intervention, was followed by protests in Latin America.
Ultimately, 42,000 American armed forces were deployed and remained there until September 1966. More than 3,000 Dominicans and 31 American servicemembers lost their lives. This was the second time that the U.S. invaded the Dominican Republic. The first time was in 1916, lasting over 8 years and resulting in the establishment of an American-sponsored puppet government in the Dominican Republic. More
Spanish authorities announced, on April 7, 1966, the recovery of a hydrogen bomb that had accidentally fallen into the Mediterranean and disappeared. The bomb was the last one to be found, out of four, that came down after a U.S. B-52 collided with a refueling tanker on January 17, 1966, over southern Spain, killing seven airmen. More
The Uniform Time Act of 1966 is signed by President Lyndon Johnson on April 14, 1966. The act mandated standard time within the established time zones and provided for Day Light Savings time (DST).
Clocks would be advanced one hour beginning at 2:00 a.m. on the last Sunday in April (Currently the second Sunday of March) and turned back one hour at 2:00 a.m. on the last Sunday in October (currently the first Sunday in November). States were allowed to exempt themselves from DST as long as the entire state did so. If a state chose to observe DST, the time changes were required to begin and end on the established dates. As of 2026, DST is not observed in the U.S. States of Hawaii, most of Arizona and the U.S. territories of American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the U.S. Virgin Islands,
Soviet cosmonaut Vladimir Komarov is killed on April 24, 1967, when the Soyuz 1 spacecraft became entangled in its main parachute at an altitude of several miles and fell back to Earth.
Dr. Martin Luther King Jr. delivers his Mountaintop Speech on April 3, 1968 at the Mason Temple in Memphis, Tennessee.
Civil rights leader Dr. Martin Luther King Jr. is shot and mortally wounded on April 4, 1968, as he stood on the second-floor balcony outside his room at the Lorraine Motel in Memphis, Tenn. He was pronounced dead at 7:05 p.m. at St. Joseph Hospital. More
The 6.5 magnitude, Los Angeles - Borrego Mountain Earthquake shook the area on April 8, 1968 at 18:28. It was the largest and most damaging quake to have hit southern California since the Kern County earthquake, 16 years earlier. It was felt as far away as Las Vegas, Fresno, and even Yosemite Valley. More
Dr. Denton Cooley implants the first complete, temporary artificial heart in a human on April 4, 1969, at the Texas Heart Institute (THI), keeping the patient, Haskell Karp, alive for 64 hours, until a suitable heart donor was found.
Karp died thirty-two hours after receiving a new human heart, from renal failure and pneumonia. The operation proved the viability of the artificial heart as a temporary measure. That first artificial heart is now in the Smithsonian.
The very first Request for Comments (RFC 1). "To propose and discuss technical methodologies applicable to internet technology", went out on April 7, 1969. The date is often cited as the symbolic birth date of the net. There is also support for Jan. 1, 1983, as the birth of the net, which was the date, the National Science Foundation’s university network backbone, a precursor to the World Wide Web, became operational utilizing the TCP/IP communication standard. More
NASA launches Apollo 13 on April 11, 1970, the seventh crewed mission in the Apollo space program and the third scheduled moon landing. Two days later, at almost 56 hours into the mission in April 13, the Apollo 13 oxygen tank 2, exploded, damaging the oxygen tank 1, the interior of the service module and blowing off the bay no. 4 cover.
With the oxygen stores depleted, the command module was unusable, the mission had to be aborted, and the crew transferred to the lunar module and powered down the command module and the mission objective changed to getting the Crew safely home.
After a lot of hard work and improvisation, the Apollo 13 spacecraft with Astronauts. Jim Lovell, Jack Swigert, and Fred Haise returned safely to earth Earth on April 17, 1970, splashing down in the Pacific Ocean . More
Note: The original Command Module pilot for this mission was Thomas "Ken" Mattingly Jr., but due to exposure to German measles he was replaced by his backup, Command Module pilot, John L. "Jack" Swigert Jr.
“Houston, we’ve had a problem…” Apollo 13 returns safely to Earth on April 17, 1970, after an oxygen tank ruptured two days into the mission. The spacecraft carried astronauts James A. Lovell, John L. Swigert and Fred W. Haise. Apollo 13 mission was to be the third manned lunar landing.
The original Command Module pilot for this mission was Thomas "Ken" Mattingly Jr., but due to exposure to German measles he was replaced by his backup, Command Module pilot, John L. "Jack" Swigert Jr. More
The first Earth Day is celebrated in the United States on April 22, 1970, to promote environmental awareness.
The U.S. Supreme Court ruled unanimously on, April 20, 1971, in Swann v. Charlotte-Mecklenburg Board of Education, that busing could be used as a tool to achieve racial integration in schools. This decision authorized judges to mandate busing to address racial imbalance in education. More
Apollo 16, the fifth of six U.S. lunar landing missions, is successfully launched on April 16, 1972 on its journey to the moon from Cape Canaveral, Florida, carrying astronauts John W. Young (Commander), Charles M. Duke (Lunar Module Pilot) and Thomas K. Mattingly (Command Module Pilot). More
The World Trade Center "Twin Towers" in New York City are officially dedicated on April 4, 1973, becoming the world’s tallest building at the time and a dominant feature of the city’s skyline. They were destroyed in a terrorist attack in 2001.
Hank Aaron, Atlanta Braves outfielder, hit his 715th career home run, on April 8, 1974, breaking Babe Ruth's home run record in Major League Baseball. The record breaking homerun occurred in the 4th inning against a Los Angeles Dodgers pitcher.
The "People Power" (the Carnation Revolution) of April 25, 1974. A largely peaceful military coup in Portugal, highlighted by civilians placing red carnations in soldiers' gun barrels, and the merging of military action and popular uprising into a massive popular movement.
The resulting profound social revolution and the establishment of lasting democratic and social changes, ended nearly half a century of authoritarian rule.
Childhood friends Bill Gates and Paul Allen found Microsoft on April 4, 1975, in Albuquerque, New Mexico. It was created to develop a BASIC interpreter for the Altair 8800, one of the first commercially successful personal computers. The company relocated to Bellevue, WA on January 1, 1979.
In 1980, Microsoft entered into a partnership with IBM to provide the operating system for the upcoming IBM PC. However Microsoft did not have one, and they purchased a non exclusive license for $25,000 to $50,000 from Seattle Computer Products (SCP) where programmer, Tim Paterson had developed an operating system called QDOS (Quick & Dirty Operating System), later renamed 86-DOS. The Operating system acquisition was strategic move that established MS-DOS as an industry standard. Microsoft and SPC later reached and agreement for $1M which gave Microsoft a full license for the operating system.
IBM officially introduced its Personal Computer (Model 5150), on August 12, 1981. Microsoft went public on March 13, 1986, at $21 per share. Its subsequent growth made Bill Gates the world's youngest billionaire by 1987.
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