During a discussion of meaningful country-specific songs in /r/AskReddit an Estonian briefly mentioned several songs used in the Singing Revolution that united their country, and set the stage for independence. I know nothing about this time and place in history, but this sounds fascinating.
What role did large folk festivals play in the culture of the Baltic States under Soviet control? Did that role change leading up to the Singing Revolution?
Was there a previous tradition of mass demonstration through song, or was this a new occurrence? What songs served to unite the demonstrators?
How and why did this Singing Revolution succeed (what factors allowed for the movement to gain momentum and spread)? How did the mass demonstrations lead to independence?
Thanks in advance.
Right off the bat: "Singing Revolution" is a good American movie about the whole thing, I recommend. Also, I'll focus on just Estonia, not the other two.
Folk festivals were nothing new, the first Song Festival was held in 1869 as a part of the larger national awakening movement, then under the Russian Empire. The official reason for organizing it was to celebrate 50 years passing from the end of serfdom in the province of Livonia (Estonia + Latvia).
The tradition of singing together came with the Moravian Church, their first mission reached Tallinn in 1729 (they also had their hand in creating the first Estonian-language Bible, an important landmark in the national awakening). They sang German religious songs and generally disliked local traditional form, like the regilaul. Meanwhile, the official Lutheran church and village schools taught German polyphonic chorus, which is how the tradition spread among the farmer folk. The Baltic German singing societies, Liedertafel, were also a great influence. The Baltic Germans held their first song festival in 1836, in Riga. A national awakening activist J. V. Jannsen wrote that every village in Germany has its own singing society and we should follow their example by borrowing the tradition. Our national awakening coincided with that of the Germans (their singing societies were a part of the awakening as well) which brought about greater differentation between local Germans and the landfolk, Undeutsch. That in turn lead to the popularization of referring to ourselves as "Estonians" rather than landfolk which lead to our own song festivals. (I don't know which songs were "important" at the time, however.)
The Soviet Union carried a facade of "we're a melting pot thus we love all the folky stuff" so the tradition of song festivals (7 held under imperial Russia, 4 under Republic of Estonia) carried over into Estonian SSR, where the first festival was held in 1947. The next one, in 1950 (breaking the tradition of 1-festival-per-5-years) was organized by Moscow's authorities and included state-friendly songs (i.e. the Internationale and the anthem of the USSR) and had a different format. It became a means of enforcing the narrative that USSR was a tolerant multicultural empire, that all these local traditions were a part of the Soviet heritage.
Everything was really sort of simplified by Gorbatchovs lack of ability to do much about protests and such (he had advertised his new, more open USSR in the world and couldn't exhibit authoritarianism without losing face), as well as glasnost aka "make stuff known to the public". Note: it's debatable how much the success of the revolution can be attributed to internal and how much to external factors (e.g. American influence). I'll just talk of the internal ones because I'm afraid I don't know enough of the external ones. Despite being named the Singing Revolution, the whole thing contained other movements as well.
The popular movement to not allow the mining of phosphorite on the territory of Estonian SSR, as it would greatly damage the environment.
The MRP-AEG society (created in 23rd of August 1987) that campaigned for the publication of the Molotov-Ribbentrop pact together with its secret protocols, and liquidation of its consequences. A public meeting of MRP-AEG was held in the Hirve park in Tallinn where many learned for the first time of the pact itself.
IME (Self-Sufficient Estonia) was proposed in 1987 and put into action in 1988 (31st of March). Immediately after (1-2nd April) a meeting of the creative intellectuals in Tallinn demanded greater political rights as well as cultural and economical independence within the USSR, a halt to migration of Russian workers into Estonian SSR and the resignation of the ministers of Estonian SSR.
During the Tallinn Old Town Days in 6th of June 1987 young folks walked from a night-time concert held in Old Town (don't know the details as to why exactly they switched locations) to the Song Festival grounds, starting the tradition of Night Song Festivals (öölaulupidu as opposed to the regular laulupidu). Lone blue-black-whites (illegal at the time) were shown among the crowd. It started as a spontaneous public event which grew to such a size that the authorities could no longer peacefully stop it.
In 14th of May 1988 an open-air concert in Tartu featured public waving of the blue-black-whites among the crowd and the Five Songs of Alo Mattiisen (which gained sentimental value as patriotic unifying songs) were performed for the first time.
In 11th of September 1988 300,000 people gathered on the Song Festival Grounds to listen to political statements/demands and to sing patriotic songs. Estonian independence was also proposed for the first time in a speech by Trivimi Velliste.
In 16th of November 1988 the Estonian SSR Supreme Council (lead by a new pro-Estonian Vaino Väljas as opposed to the Brezhnev age pro-Russian Karl Vaino) adopted the Estonian Declaration of Sovereignty (which declared the superiority of Estonian SSR laws over USSR laws in the territory of Estonian SSR) but it was overruled by Moscow 10 days later.
In 7th of December 1988 the Estonian SSR Supreme Council adopted a constitutional amendment by which Estonian was declared the state language.
In 24th of February 1989 the Estonian National Heritage Society, the Estonian National Independence Party and the Estonian Christian Union appealed to organize a general registration of the citizens of the Republic of Estonia and free elections to the representative body of Estonia, the Congress of Estonia, which assembled in 1990.
In 23rd of August 1989 the most famous event, the Baltic Way/Chain was held to commemorate the signing of the MRP 50 years earlier. A tri-language song, "Wake up, Baltics", was written specifically for the event to be a kind of a Baltic anthem. The event was very much disliked in Moscow where it was declared nationalistic hysteria.
In 19th-21st August 1991 a coup was organized in Moscow by hard-line communists to return to a more authoritarian system. At the same time, in 20th of August, the Estonian SSR Supreme Council adopted the declaration of Estonian independence from USSR.