U.S. National Guard troops block off Beale Street in Memphis, Tennessee, as Civil Rights marchers wearing placards reading, "I AM A MAN" pass by on March 29, 1968. It was the third consecutive march held by the group in as many days. #

The Supremes, with Diana Ross, front, Cindy Birdsong, and Mary Wilson dance with their arms in the air as they perform at the annual "Bal pare" party in Munich, West Germany, on January 21, 1968. The American trio was backed by the West German Rolf Hans Mueller big band and was celebrated with thundering applause. #

The flag of South Vietnam flies atop a tower of the main fortified structure in the old citadel as a jeep crosses a bridge over a moat in Hue during the Tet Offensive in February of 1968. #

South Vietnamese General Nguyen Ngoc Loan, chief of the national police, fires his pistol, executing suspected Viet Cong officer Nguyen Van Lem (also known as Bay Lop) on a Saigon street on February 1, 1968, early in the Tet Offensive. Lem was suspected of commanding a death squad which had targeted South Vietnamese police officers that day. The fame of this photo led to a life of infamy for Nguyen Ngoc Loan, who quietly moved to the United States in 1975 and opened a pizza shop in Virginia. #

A U.S Marine with several days of beard growth sits in a helicopter on July 18, 1968, after being picked up from a landing zone near Con Thein on the southern edge of the demilitarized zone in South Vietnam. His unit had just been relieved of duty after patrolling the region around the DMZ. #

A speaker addresses a mass rally in support of democracy organized by the youth of Prague at the Old Town Square in Prague, Czechoslovakia, on May 18, 1968. During a period called the "Prague Spring," Alexander Dubček, the newly-elected leader of the Warsaw Pact nation, enacted numerous reforms loosening state control and expanding individual rights, which both encouraged citizens and angered the Soviet Union. #

By late summer, talks between the Soviets and Czech leaders were not going the way the Kremlin wanted, so more than 2,000 tanks and thousands more Warsaw Pact troops invaded and occupied the country in August. This column of Soviet tanks was lined up in a street in Prague, Czechoslovakia, near the Old Town Square, on August 28, 1968, after Czech leaders had returned from negotiations with the Russians. #

Prague residents surround Soviet tanks in front of the Czechoslovak Radio station building in central Prague during the first day of a Soviet-led invasion of Czechoslovakia on August 21, 1968. Within a year, Dubček was removed from office, his reforms were undone, and a more Soviet-controlled government was installed. #

American figure skater Peggy Fleming practices on an outside rink on February 1968 in Grenoble, in the French Alps, during the 1968 Winter Olympic Games. Fleming took the gold medal in women's figure skating. #

Fashion in 1968. Left: A male model wears a silk jersey print pajama leisure suit, sandals, and a necklace at a fashion show in New York on January 9. The show was entitled "Clothing for the Emancipated Man." Center: A sculpted silver necklace designed by Pierre Cardin features a diamond worth $60,000. The necklace is built into the halter that is part of a long black crepe evening gown presented in his spring collection in Paris, France, in February. Right: A cocktail dress of printed pure silk with a full skirt, a creation by the Fontana Sisters fashion house of Rome, to be presented at the upcoming Italian spring-summer ready-to-wear fashion show that opened in Florence on November 6, 1968. #

One of the last pictures to be taken of Dr. Martin Luther King Jr., as he spoke to a mass rally in Memphis on April 3rd, saying he would not halt his plans for a massive demonstration scheduled for April 8 in spite of a federal injunction. #

Civil-rights leader Andrew Young (left) and others stand on the balcony of the Lorraine Motel pointing in the direction of an assailant after the assassination of civil-rights leader Dr. Martin Luther King Jr., who is lying at their feet, in Memphis, Tennessee, on April 4, 1968. #

This aerial view shows clouds of smoke rising from burning buildings in northeast Washington, D.C., on April 5, 1968. The fires resulted from rioting and demonstrations after the assassination of Dr. Martin Luther King Jr. #

Firemen battle a blaze on 125th Street in Harlem, New York, on April 4, 1968, after a furniture store and other buildings were set on fire after it was learned that civil-rights leader Dr. Martin Luther King Jr. had been assassinated. #

President Johnson called federal troops into the nation's capital to restore peace after a day of arson, looting, and violence on April 5, 1968. Here, a trooper stands guard in the street as another (left) patrols a completely demolished building. #

Coretta Scott King, the widow of Martin Luther King Jr., walks on the arm of Dr. Ralph Abernathy, her husband's successor as head of the Southern Christian Leadership conference, leading about 10,000 people in a memorial march to the slain Dr. King. The King children, Yolanda, Martin III, and Dexter are at left with Harry Belafonte. Reverend Andrew Young marches next to Dr. Abernathy. #

Original caption: Dr. Timothy Leary holds a conference in New York City on February 21, 1968. The LSD advocate said he is tuning in with peaceniks and “Yippies” and hopes to have a million young people in Chicago during the Democratic Party’s convention in August. He said he hopes they will disrupt the convention through “Flower Guerrilla” warfare. At left is Abbie Hoffman, who said he is an organizer and at right is Jerry Rubin, peace movement worker. #

1968 was truly a year of protest around the world. Here in Rio de Janeiro, Brazil, state police cavalry charge students attending a memorial mass for Edson Luis de Lima Souto, a student killed by police, at Candelaria Church on April 4, 1968. Edson had been part of an earlier protest over high prices in a restaurant in downtown Rio, and was shot by police who were trying to remove students from premises. #

Violent clashes between policeman and students take place during the May 1968 protests in Paris, France. [Editor's note: This photo replaces a previous image in this position that had been mislabeled by the source.] #

The Beatles pose together on February 28, 1968. From left are Paul McCartney, John Lennon, Ringo Starr, and George Harrison. This was the year they released the White Album. #

American actor Gary Lockwood on the set of 2001: A Space Odyssey, written and directed by Stanley Kubrick. The groundbreaking film premiered in April of 1968, and earned the Academy Award for Best Visual Effects. #

A propaganda image from China's Cultural Revolution. In 1968, China was in a phase of their Cultural Revolution where Chairman Mao Zedong's cult of personality was still being elevated, and intellectuals and disloyal citizens were being forced into labor camps or exiled to remote farming regions. Original caption: Members of the Sichuan Province Revolving Committee unite with civilians and soldiers to work in the fields on August 26, 1968. #

Federal Nigerian troops walk along a road near Ikot Expene, Nigeria, to the frontier with Biafra, a few miles away, on October 13, 1968. On the roadside, two emaciated Nigerian boys slowly die from starvation and malnutrition. Biafra was a breakaway state within Nigeria that fought a war for independence from 1967 to 1970, ending after years of fighting and a crippling blockade by Nigeria resulted in the deaths of between 500,000 and two million Biafran civilians by starvation. #

A street scene from Pittsburgh, Pennsylvania, Grant St. at 5th Ave. on August 24, 1968. See the same scene today in Google Street View. #

Original caption: A Feminine First. Mexico City: Mexico's Norma Enriqueta Basilio, the first woman in the history of the modern Olympic Games to light the Olympic Fire, runs up the 90 steps with the Olympic Torch during the opening ceremonies here on October 12, 1968. #

Tommie Smith and John Carlos, gold and bronze medalists in the 200-meter run at the 1968 Olympic Games, engage in a victory stand protest against unfair treatment of blacks in the United States. With heads lowered and black-gloved fists raised in the black power salute, they refused to recognize the American flag and national anthem. Australian Peter Norman is the silver medalist. #

Senator Robert F. Kennedy is surrounded by hundreds of people as he leans down to shake hands during a presidential campaign appearance at a street corner in central Philadelphia on April 2, 1968. Kennedy had declared his candidacy for the presidency of the United States only weeks earlier, on March 16. #

Senator Robert Kennedy lies sprawled, semi-conscious in his own blood after being shot in the head and neck while busboy Juan Romero tries to comfort him in kitchen in the Ambassador Hotel in Los Angeles, California, on June 5, 1968. A Palestinian immigrant named Sirhan Sirhan, who was angry with Kennedy over his support for Israel, shot Kennedy three times. Sirhan remains in prison to this day, last denied parole in 2016. #

Coretta Scott King, widow of Martin Luther King Jr., walks past the casket containing the body of the assassinated Senator Robert F. Kennedy in St. Patrick's Cathedral in New York City on June 7, 1968. #

Youths prepare to board buses for Chicago in August of 1968. Peace activists and anti-war groups organized to travel to Chicago to demonstrate outside the 1968 Democratic National Convention. #

Mike Wallace, a CBS newsman, is hustled off the Democratic National Convention floor in the aftermath of a row between delegates and security officers during the nominating session on August 28, 1968 in Chicago. He was taken up a ramp to a second-floor room. #

Vice President Hubert Humphrey and his running mate, Sen. Edmund S. Muskie, with their wives shown at the final session Democratic Convention in Chicago following their nominations for president and vice president, on August 29, 1968. #

Members of the Black Panthers gather in front of entrance to the Alameda County Courthouse in Oakland, California, on July 15, 1968, to protest the trial of Huey Newton, 26, the founder of the Black Panthers. Newton went on trial for the slaying of an Oakland policeman and for wounding another officer on October 28. #

Original caption: Miami policemen, one holding the man's arm and the other with an arm lock on his neck, drag away a Negro youth during a clash between police and rioters in that city's predominantly Negro Liberty City district on August 8, 1968. #

Helicopters fly low during Operation Pegasus in Vietnam on April 5, 1968. They were taking part in the operation to relieve the Khe Sanh marine base, which had been under siege for the previous three months. #

Evidence of the My Lai Massacre. A photograph of Vietnamese women and children in My Lai before they were killed by U.S. soldiers in the massacre on March 16, 1968. According to court testimony, they were killed seconds after the photo was taken. The woman on the right is adjusting her blouse buttons because of a sexual assault that happened before the massacre. Image taken from Volume III, Book 6, of the Report of the Department of the Army Review of the Preliminary Investigations into the My Lai Incident, photographed by United States Army photographer Ronald L. Haeberle. #

United States President Lyndon B. Johnson listens to a tape recording from his son-in-law Captain Charles Robb at the White House on July 31, 1968. Robb was a U.S. Marine Corps company commander in Vietnam at the time. Robb was later awarded the Bronze Star and, after returning home, became governor of Virginia in 1982, and later a senator for the same state. #

Original caption: Several hundred hippies gathered at "Hippie Hill" in San Francisco's Golden Gate Park for a happening at which several bands played rock 'n' roll music. Most of the hippies sat and listened, but some just couldn't keep from dancing to the rhythms. #

Mexican army soldiers crouch with weapons ready in Mexico City's Tlatelolco district, in this October 2, 1968 photo. The truth behind the stunning assault on a peaceful democracy protest known as the Tlatelolco Massacre, in which some 300 people are believed to have been killed, remains largely hidden by government and military secrecy. #

Soldiers cut a student's hair after he was arrested during the first hour and a half of shooting in the Tlatelolco area in Mexico City on October 3, 1968. Another student stands against the wall. #

SRI’s Bill English, the engineer who built the first computer mouse prototype, prepares for the December 9, 1968 "mother of all demos." The demonstration is hailed as one of the most significant technological presentations in history, showcasing technologies that have become what we now know as modern computing. He gave the first public demonstration of a computer mouse, a graphical user interface, windowed computing, hypertext, word processing, video conferencing, and much more. #

French Foreign Minister Michel Debre and U.S. President Lyndon Johnson watch television coverage of the flight of the Saturn 1 B Rocket launching from Cape Kennedy, Florida, on on October 11, 1968, in the White House Office in Washington, D.C. #

A heavy beard covers the face of astronaut Walter M. Schirra Jr., Apollo 7 commander, as he looks out the rendezvous window in front of the commander's station on the ninth day of the Apollo 7 mission on October 20, 1968. Apollo 7 was the first Apollo mission to carry a crew, and it made 163 orbits around the Earth in 10 days, setting the stage for Apollo 8, which was heading to the moon. #

Apollo 8, the first manned mission to the moon, entered lunar orbit on Christmas Eve, December 24, 1968. That evening, the astronauts—Commander Frank Borman, Command Module Pilot Jim Lovell, and Lunar Module Pilot William Anders—held a live broadcast from lunar orbit, in which they showed pictures of the earth and moon as seen from their spacecraft. Said Lovell, "The vast loneliness is awe-inspiring and it makes you realize just what you have back there on Earth." They ended the broadcast with the crew taking turns reading from the book of Genesis. #