April 9 Tragedy (also known as the massacre of Tbilisi or Tbilisi tragedy) refers to the events in Tbilisi, Georgian Soviet Socialist Republic, on April 9, 1989, when an anti-Soviet, pro-independence and nationalist demonstration was crushed by the Soviet Army, resulting in 21 deaths and hundreds of injuries. April 9 is now remembered as the National Unity Day (Georgian: ეროვნული ერთიანობის დღე, romanized: erovnuli ertianobis dghe), an annual public holiday.

In the Georgian SSR, the anti-Soviet movement grew more active in 1988. Political groups opposed to the Soviet Union organized a number of protests and gatherings in Tbilisi. The conflict between the Soviet government and Georgian nationalists deepened after the so-called Lykhny Assembly on March 18, 1989, when several thousand Abkhaz demanded secession from Georgia and restoration of the Union republic status of 1921–1931. In response, the anti-Soviet groups organized a series of unsanctioned meetings across the republic, claiming that the Soviet government was using Abkhaz separatism in order to oppose the pro-independence movement.

The protests reached their peak on April 4, 1989, when tens of thousands of Georgians gathered before the House of Government on Rustaveli Avenue in Tbilisi. The protesters, led by the Independence Committee (Merab Kostava, Zviad Gamsakhurdia, Giorgi Chanturia, Irakli Bathiashvili, Irakli Tsereteli and others) organized a peaceful demonstration and hunger strikes, demanding the punishment of Abkhaz secessionists and restoration of Georgian independence.

Local Soviet authorities lost control over the situation in the capital and were unable to contain the protests. First Secretary of the Georgian Communist Party Jumber Patiashvili asked USSR leadership to send troops to restore order and impose curfew.

In the evening of April 8, 1989, Colonel General Igor Rodionov, Commander of the Transcaucasus Military District, ordered his troops to mobilize. Moments before the attack by the Soviet forces, the Patriarch of Georgia Ilia II addressed the demonstrators asking them to leave Rustaveli Avenue and the vicinity of the government building due to the danger which accumulated during the day after appearance of Soviet tanks near the avenue. The demonstrators refused to disband even after the Patriarch's plea. The local Georgian militsiya (police) units were disarmed just before the operation.

On April 9, at 3:45 a.m., Soviet APCs and troops under General Igor Rodionov surrounded the demonstration area. Later, Rodionov claimed in his interview that groups of Georgian militants attacked unarmed soldiers with stones, metal chains and rods. The Soviet troops received an order from General Rodionov to disband and clear the avenue of demonstrators by any means necessary.

The Soviet detachment, armed with military batons and spades (a favorite weapon of Soviet special forces), advanced on demonstrators moving along Rustaveli Avenue. During the advance, the soldiers started to attack demonstrators with spades, inflicting injuries both minor and serious to anyone who was struck.

One of the victims of the attack was a 16-year-old girl who tried to get away from the advancing soldiers, but was chased down and beaten to death near the steps of the government building, receiving blows to the head and chest. She was dragged out of the area by her mother, who was also attacked and wounded. This particularly violent attack was recorded on video from the balcony of a building located on the other side of the avenue. The video was used in the aftermath as evidence during Soviet politician Anatoly Sobchak's Parliamentary commission on investigation of events of April 9, 1989. Groups of Soviet soldiers were reported to chase individual victims, rather than dispersing the crowd.