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In the early hours of August 21, 1968, Warsaw Pact troops invaded Czechoslovakia to crush the Prague Spring, the reform movement led by Alexander Dubček. Soviet tanks occupied Prague amid the passive resistance of thousands of citizens. The invasion buried any hope of reform within the Soviet bloc for twenty years.

On August 21, 1991, Latvia declared the full restoration of its independence, taking advantage of the chaos of the failed coup in Moscow. Like Estonia and Lithuania, it had been annexed by the Soviet Union in 1940. The three Baltic republics became the first to leave the USSR, and in 2004 they joined the European Union and NATO.

On August 18, 1966, an Australian battalion of just 108 soldiers withstood a three-hour assault by more than 2,000 Viet Cong guerrillas at the Battle of Long Tan in Vietnam. Australian casualties were 18 dead and 24 wounded, against more than 500 on the enemy side. It is considered the most heroic action of the Australian army in the Vietnam War.