The Gwangju massacre (광주 민주화 운동) refers to the violent suppression of a popular uprising in the city of Gwangju, South Korea from May 18 to May 27, 1980. For the period of Chun Doo-hwan's reign, the incident was officially regarded as a rebellion inspired by Communist sympathisers. But after civilian rule was reinstated, the incident received recognition as an effort to restore democracy from military rule. The government made a formal apology for the incident, and a national cemetery, the May 18 National Cemetary, was established for the victims.
The death toll of the massacre has been subject to considerable dispute. The official investigation by the government in the 1990s found the number of civilians confirmed dead to be 207.  In addition they found 987 "Other Casualties" who suffered substantial injury. However, a BBC report indicated that these numbers may be conservative.  Estimates prepared by dissident groups during the period of military government rule, and opposition parties in the late-1980s such as the Peace and Democracy Party, claimed that one to two thousand had died.  However, detailed information about the identities of the dead has not been provided to back up these claims.
May 17, 1980
After the Coup d'état of December Twelfth (1979) in Seoul, General Chun Doo-hwan declared martial law on May 17, 1980 to suppress student demonstrations around the country. The next day, students in Gwangju protested at the gate of Chonnam National University against the closing of the university, when armed forces blocking the university responded with violent means. After the incident, students moved into the downtown area, where they were joined by the citizens of the city. The growing crowd was met by the use of force, including gunfire, that caused some fatalities.
May 20, 1980
As the news of the fatalities spread, on May 20, protesters burned down the MBC local station which, under effective government control, portrayed the protests as hooligans led by Communist agents. By May 21, some 300,000 people had joined the protest against the General's power; weapons depots and police stations were looted of their weapons and the civil militias, known as the Citizen Army, beat back the armed forces.
With all routes and communications leading in and out of the city blocked by armed forces, a civilian body was formed to maintain order and conduct negotiations with the government. Although order was well maintained, a number of negotiations to resolve the situation failed to achieve any results.
May 27, 1980
On May 27, airborne and army troops from five divisions were inserted and defeated the civil militias in the downtown area in only 90 minutes. To this day, a total of 20,000 soldiers are located in Gwangju, which only has a population of approximately 740,000.
Allegations of US involvement
Tim Shorrock, through his analysis of recently declassified U.S. government documents, made the following conclusions regarding U.S. involvement in the incident:
- Senior officials in the Carter administration, fearing that chaos in South Korea could unravel a vital military ally and possibly tempt North Korea to intervene, approved Chun's plans to use military units against the large student demonstrations that rocked Korean cities in the spring of 1980.
- U.S. officials in Seoul and Washington knew Chun's contingency plans included the deployment of Korean Special Warfare Command troops, trained to fight behind the lines in a war against North Korea. The Black Beret Special Forces, who were not under U.S. command, were modeled after the U.S. Green Berets and had a history of brutality dating back to their participation alongside American troops in the Vietnam War.
- On May 22, 1980, in the midst of the Gwangju uprising, the Carter administration approved further use of force to retake the city and agreed to provide short-term support to Chun if he agreed to long-term political change. At a White House meeting on that date, plans were also discussed for direct U.S. military intervention if the situation got out of hand.
Other historians, such as Don Oberdorfer in his book The Two Koreas, paint a picture of much more limited US involvement with Washington unaware of the amount of force Chun planned to use.