[5] Following the withdrawal of the Indian Peace Keeping Force, the Sri Lanka Army expanded its presence in the Pooneryn area establishing a permanent base in 1991 to counter LTTE movements across the Kilali lagoon from the Jaffna peninsula which was under its control.

The Sri Lanka Navy deployed a detachment at Pooneryn to monitor and interdict LTTE movements in the Kilali lagoon.

[4] Six weeks later the LTTE launched Operation Thavalai to destroy the isolated military base in Pooneryn and the detachment at Nagathevanthurai.

[6] On 11 November, around 2:00 a.m., the LTTE launched a massive attack from land and the lagoon with 600 cadres, simultaneously engaging the Nagathevanthurai naval detachment and the army defence lines in Pooneryn.

The LTTE infiltrated a specially trained group of cadres through the forward defence lines, with the mission of overrunning the mortar positions and the two T55 tanks.

With the battalion headquarters of the 3rd Gajaba being overrun, the garrison lost contact with the Northern Command under Major General Rohan Daluwatte at the Palaly Military Base.

Remaining units that regrouped around the battalion headquarters of the 1st Sri Lanka Light Infantry were able finally to contact the Elephant Pass Military Base.

[4] [8] Following the attack, the three service commanders flew to Palaly, setting up their operational joint headquarters there to plan relief for the besieged garrison.

With covering fire from Shanghai class fast gunboats, the newly formed Special Boat Squadron, led by Lieutenant Commander Ravindra Wijegunaratne carried out the initial landings from two inshore patrol craft securing a beachhead.

[4] The 3rd Gajaba had suffered 149 killed and 115 missing, which included 4 officers and its second in command Major U. Hemapala who was posthumously promoted to the rank of lieutenant colonel.

On 14 November, badly wounded, Lieutenant Nissanka, a platoon commander in the 3rd Battalion, Gajaba Regiment, which held the forward defence line till dawn, ordered the remainder of his platoon to withdraw with its wounded and to cover the withdrawal he ran at the attacking enemy with two primed grenades, killing himself and enemy fighters in the process.

Major General Rohan Daluwatte had claimed that five battalions from his command had been moved to the Eastern Province to conduct facilitate elections, contributed to the disaster.

Lieutenant General Waidyaratne refuted these by stating the Daluwatte should have managed with resources at his disposal which included 31,370 troops under the Northern Command at the time of the attack.

Daulagalab for shortcomings in the preparedness of the Pooneryn base to face such an attack, with over 600 of the troops stationed at the time being fresh recruits and disciplinary action hadn't been taken following the Battle of Janakapura in July 1993 which had found fault with Major General Rohan Daluwatte and three others.

[13] In November 1993, Amnesty International appealed to the LTTE to publicly acknowledge if it had captured any soldiers during the battle and to treat any under the terms of the Geneva Conventions and allow access to International Committee of the Red Cross (ICRC), after the Sri Lankan military claimed that about 70 soldiers had been taken prisoner by the LTTE during the battle.