[3] At the time it was the largest combined services operation undertaken by the armed forces deploying multiple brigade-size formation, becoming the first conventional warfare engagement on Sri Lankan soil after the end of British colonial rule.

This gave the LTTE a free hand in much of the Jaffna peninsula, reducing the Sri Lankan government's control over this area.

[7] In early 1987 the Sri Lankan military formulated a plan to restore government control over the area dominated by the LTTE.

Denzil Kobbekaduwa, consisting of the 3rd Sri Lanka Light Infantry (commanded by Lt. Col. Naradha Wickramarathne and Maj. Sarath Fonseka) and the 3rd Gajaba Battalion was tasked with the main push into the Vadamarachchi, with elements of engineering units attached.

The Sri Lanka Navy deployed its Shanghai class fast gunboats for naval bombardment and an array of smaller vessels for coastal operations enforcing an exclusion zone around the coast of Vadamarachchi.

[9][10][11][12] On Good Friday, 17 April 1987, the LTTE carried out the Aluth Oya massacre, killing 127 civilians, including children and women.

This was followed four days later by a massive car bomb blast near the central bus stand in Pettah, Colombo, which resulted in 113 deaths of civilians.

In one of these forays the army killed LTTE Jaffna District leader Anthony Kaththiar (alias Radha), who had carried out the Anuradhapura massacre.

At first light, air force planes dropped leaflets advising the civilian population to take shelter in designated safe zones, and a dusk-to-dawn curfew was enforced across the peninsula.

The first day of the battle depended mainly on the field engineer squadron, as sappers—constantly under fire—neutralized and removed mines and booby traps left by LTTE cadres.

The sappers cleared a path across the minefield although under fire from LTTE bunkers, allowing the 1 Gajaba Regiment to move forward by the afternoon.

To the south, a force advanced from Elephant Pass to Iyakachchi and then to Sornampattu, with the objective of reaching Chempionpattu to seal off the southern part of Vadamarachchi, which it achieved.

Reaching the coast, troops from the 1st Brigade, defeating the defensive line commanded by LTTE leader Soosai, made a 90-degree turn undertaking a pincer movement to capture Valvettithurai.

The troops found bunkers in the town with strong concrete walls that withstood 37mm shells of the gunboats as well as a militant training camp and a workshop that manufactured mortars called "baba".

[9] With the objective of Phase One achieved, the second stage of this operation was launched on June 3, 1987, with a thrust towards Achchuveli, the goal of which was to capture the city of Jaffna, less than 20 km away.

President Jayewardene and Minister Athulathmudali were furious, as they saw this as a direct intervention by India in the internal matters of Sri Lanka, and a strong protest was lodged with the Indian High Commissioner in Colombo.

After the navy threatened to open fire if the boats crossed into Sri Lankan territorial waters, the flotilla turned back.

7 Squadron armed with Matra Magic II AAMs with the threat that "force" would be used if opposed by the Sri Lanka Air Force; 22 tons of what were claimed to be humanitarian relief supplies were dropped in the Jaffna area on June 4 in Operation Poomalai, in what was termed a violation of territorial sovereignty by Sri Lanka.

The abrupt halt of the second phase of the operation drastically affected morale of the troops involved, as the military and many in Sri Lanka believed victory was certain with the capture of Jaffna and the LTTE leadership that was trapped.