Observers in the late 1980s counted at least thirty separate guerrilla groups of which five, including the LTTE, were the most important (see The Tamil Insurgency , ch. 5). The other four major groups were the Eelam People's Revolutionary Liberation Front (EPRLF), led by K. Padmanabha, the Tamil Eelam Liberation Organization (TELO), led by Sri Sabaratnam until he was killed by the LTTE assassins in May 1986, the Eelam Revolutionary Organization of Students (EROS), led by V. Balakumar, and the People's Liberation Organization of Tamil Eelam (PLOTE), headed by Uma Maheswaran. These groups differed significantly in terms of strategies and ideologies. EROS was said to prefer acts of economic sabotage. In March 1985, the LTTE, EPRLF, TELO, and EROS formed a united front organization, the Eelam National Liberation Front (ENLF). PLOTE, probably the most genuinely Marxist-Leninist of the five major guerrilla groups, remained outside the coalition. By mid-1986, ENLF had become largely inoperative after the LTTE quit, although the other groups sought to form a front without its participation.

The Liberation Tigers proceeded to devour their rivals during 1986 and 1987. TELO was decimated in 1986 by repeated LTTE attacks. During 1987 the Tigers battled not only Indian troops but members of PLOTE and the EPRLF.

The year 1983 can be regarded as a psychological turning point in the ethnic crisis. The brutal anti-Tamil riots of July in Colombo and other towns, and the government's apparent lack of concern for Tamil safety and welfare seemed to rule out a peaceful resolution of differences between Tamils and Sinhalese. The riots were touched off by the July 23 killing of thirteen Sinhalese soldiers by LTTE guerrillas on the Jaffna Peninsula. According to Tambiah, the mutilated corpses were brought to Colombo by their comrades and displayed at a cemetery as an example of the Tigers' barbarism. In an explosion of rage, local Sinhalese began attacks on Tamils and their property that spread out from Colombo District to other districts and resulted in at least 400 casualties (the official figure) and perhaps as many as 2,000 (an estimate by Tamil sources). Fifty-three Tamil prisoners were killed under questionable circumstances at the Welikade Prison outside Colombo. Damage to property, including Tamil-owned shops and factories, was initially estimated at the equivalent of US$150 million, probably a low figure.

The authorities, seemingly paralyzed during the bloody days of July 24 to July 31, did little or nothing to protect the victims of mob violence. Curfews were not enforced by security personnel even though they were required under a nationwide state of emergency in effect since the May by-elections. Jayewardene withdrew to his presidential residence, heavily guarded by government troops, and issued a statement after the riots that "the time has come to accede to the clamor and the national respect of the Sinhala People," that expressed little sympathy for the sufferings of the Tamils.

There was ample evidence, repo 137a orted in the Indian and Western media, that the violence was more a carefully planned program than a totally spontaneous expression of popular indignation. According to a report in the New Delhi publication, India Today, "the mobs were armed with voters' lists, and detailed addresses of every Tamil-owned shop, house, or factory, and their attacks were very precise." Other sources mentioned the central role played by Minister of Industry and Scientific Affairs Cyril Mathew in providing personnel for the violence and the ease with which the mobs found transportation, including government vehicles, to move from place to place.

According to political scientist James Manor, the eagerness of powerful politicians such as Mathew to stir up ethnic trouble stemmed at least in part from factional struggles within the ruling UNP. Mathew reportedly used the riots to compromise the aging and seemingly indecisive Jayewardene and undermine support for the chief executive's all-but-designated successor, Prime Minister Ranasinghe Premadasa. According to India Today reporting in August 1983, five UNP factional groups, including Mathew's and Premadasa's, competed for influence. With deep reservoirs of anti-Tamil sentiment among poorer Sinhalese to draw upon, Mathew could not be ignored in any post-Jayewardene political arrangement within the UNP. His schemes, however, ultimately backfired. In December 1984, Mathew was obliged to resign from the cabinet for opposing negotiations between the government and the Tamils on regional autonomy, and he subsequently faced expulsion from the party.

The 1983 violence had a caste as well as ethnic dimension. Mathew was a leader of the Vahumpura caste. This group has a lower status than the politically dominant Goyigama caste but comprises more than one-third of the Sinhalese population. Traditionally, Vahumpura occupations included the making of jaggery (brown sugar derived from palm sap) and domestic service in higher caste households. Nevertheless, they trace their descent from the attendants of Mahinda, the brother or son of the Indian emperor Asoka, who came to Sri Lanka as a Buddhist missionary in the third century B.C. and thus claimed an esteemed status among Sinhalese Buddhists. The Vahumpura also had been actively involved in commerce, but in the 1970s and early 1980s they were forced out of the business by their Sinhalese Karava and Tamil competitors. The resultant decline in their fortunes was a source of much resentment toward the other groups.

Some observers speculated that the LTTE had moderated to a slight degree its attacks against government forces in the north, because of the presence of Tamil "hostages" in Colombo and other Sinhalese-majority urban areas, but that the July 1983 riots removed such inhibitions. The vicious cycle of violence intensified as attacks by the LTTE and other groups against troops brought harsh retaliation against Tamil civilians, especially in the Jaffna Peninsula. Reports issued by Amnesty International, the London-based human rights group, told of random seizures, tortures, and executions of hundreds of young Tamil men by the armed forces in Northern and Eastern provinces. These actions forced the great majority of Sri Lankan Tamils, whatever their point of view on the goals or methods of the guerrillas, into the arms of the extremists. In the words of one observer, the Tamil population in the north was "visibly afraid of the Tigers, but they disliked the [Sri Lankan] Army even more." As the civil war intensified, government troops were besieged inside the seventeenth-century Jaffna Fort, and most areas of Jaffna City and the surrounding countryside were under Tiger control. The government ordered serial bombings of the city. Thousands of Tamils sought refuge from government attacks across the Palk Strait in India's Tamil Nadu State. As indignation among Tamils in India grew over the atrocities, Colombo was filled with rumors of an impending Indian invasion that would have resulted in a permanent division of the island.

Data as of October 1988