Latvia, together with Estonia and Lithuania, was annexed by the Soviet Union in 1940. While there was relatively little resistance to the occupation, many Latvians remained unhappy with it and waited for a chance to regain independence. Such a chance came in 1980s when Gorbachev attempted to reform the Soviet Union. In particular, Gorbachev's glasnost policy allowed more freedom of speech in the Soviet Union than ever before.
Latvia's independence movement started with small demonstrations for independence and human rights in 1986. The first demonstrations, organized by Helsinki-86, were, however, suppressed by the government of Latvian SSR. The breaking point came in summer 1988. Many prominent Latvians publicly announced their support for increased autonomy for Latvia. Latvian newspapers started writing about aspects of Latvian history which had been banned during the Soviet period (for example, how Latvia had been occupied in 1940). The flag of Latvia which had been banned during the Soviet period was brought back. To summarize, a strong resurgence of Latvian national identity had started.