It started with the most atrocious constitutional amendment in june 15 , 1956 making sinhalese as the official language which internally meant that they are depriving all basic rights of tamils there.This clearly made them at least at that time , if not before an oppressed nationality.
Selvanayagam , anticipating this amendment went a peaceful rally in june 5 , 1956 from galle face hotel where a lot of tamils gathered to the lankan parliament. Suddenly and without announcement the sinhalese gathered as a mob and began to throw stones in order to disrupt the rally. But selva , a quintessential gandhian showed a great deal of patience and its in the parliament records that amidst of great rain , amirthalingam and sundaram entered the parliament with blood inundating from their body due to the stone attack.
After hearing the news about the peace rally , sinhalese on the same day at about 5 pm in a place called Gal Oya started vandalising tamil shops , houses and indulged in looting and raping. About 150 tamilians were massacared.This is about a series of incidents which happened between 5th and 15th.
This problem , according to me has to be analysed from the pre-colonisation period. When the imperialistic forces were really under threat by natives in many countries , Srilankans ( both sinhalese and tamils) didnt wage a substantial war against british.
Even after an era of 150 years of rule by the british only 5% of sinhalese were able to read and write in english.But tamils being an ethnic minority managed well in this regard and came out with flying colors.They realised the value of education and technology and they actively joined in schools and colleges. This invigorated wrath from the other side , though sinhalese were majority in provinces like inner part of the island and the south , they occupied miniumum governtment positions.
Before selvanayagam , tamils had G.G.Ponambalam as their representative , he was a lawyer. It was in 1944 when the british government appointed Lord soulbury commission to bring constitutional amendments in lanka.GGP represented tamils in this conference and he created a party called as All Ceylon Congress.His proposition was " to give 50% representation to sinhalese and to give the rest to ethnic tamils , muslims and to indian tamils working in tea estates" . But it was rejected and yet GGP became famous among tamils as he was the only voice at that period of time.
Stephen dudley senanayaka became the first prime minister of lanka in october 1947 and during these days and even before british noticed the wealth in kandi mountains and they called indian tamils to work here. Why them in particular?.Because sinhalese were not willing to bend their backs in menial works but tamils due to their poverty rushed to lanka.
Tamils migrated to lanka , called their relations there and lanka became their home land soon.And in February 4 , 1948 srilanka got their freedom from british and to be honest they were really blinking what to do next as they were comfortable with british earlier in the past.This most inhuman act of cancelling citizenship of migrant tamils happened in 1948.In short the ulterior motive was to drive out all the tamils.
In december 10 , 1948 selvanayagam gave this speech in the parliament
" This act completely denies the basic rights of tamils. We cant remain silent just because this act was restricted to indian tamils , the same scenario may happen to us ( lankan ethnic tamils) in the future. I fear that linguistic divide will reach its culmination in the near future , as the lankan government is taking all possible steps to oppress tamilians. We have to stop it right now"
His rational fear actually became the impending reality later.