The Operation Liberation or Vadamarachchi Operation, the military offensive carried out by the Sri Lankan military during May to June 1987, to re-gain the territory of Vadamarachchi in Jaffna peninsula from the LTTE control. This military offensive marked in Sri Lankan military history as first ever engaged in conventional warfare in Sri Lankan soil after the British colonial rule.

Brigadier Denzil Kobbekaduwa and Colonel Vijaya Wimalaratne are the two key military personnel who committed themselves to gain the victory for the government troops. Former Sri Lankan President Junius Richard Jayewardene and minister of National Security Lalith Athulathmudali given the political leadership for the operation until the government of India violated the Sri Lankan air space using air force to drop food over Jaffna (Operation Poomalai) on June 04 1987 which forced to accept Indo-Sri Lankan Accord.

The offensive started on May 26 1987 under the leadership of the two commanders with 8,000 troops from several battalions from Gemunu Watch (Under the Command of Lt. Colonel Vipul Botheju and Lt. Colonel Wasantha Perera), Gajaba Regiment (under the Command of Lt. Colonel Sathis Jayasundara and Major Gotabaya Rajapakse) and Sri Lanka Light Infantry (Under Lt. Colonel Naradha Wickramarathne), supported by the Sri Lanka Air Force. The difficulty for the troops to out from Thondamanaru area because LTTE exploded the Thondamanaru bridge to delay the troops reaching Valvettithurai, the native place of LTTE leader V. Prabhakaran. Eastern side of Thondamanaru was heavliy mined by the LTTE and clearing of the mines and booby traps were left to a field engineer Squadron of the Sri Lanka Engineers commanded by Major Lucky Rajasinghe. First day of the battle belong to the heroics of field engineer squadron which suffered 42 deaths in a span of 4 hours, yet broke through the mine field. On May 28 troops managed to capture Udupiddy and Valvettithurai and also another military column (Commandos, under the command of Major Sarath Handapangoda) captured Nelliady and advanced towards Point Pedro without giving any possibility to re-grouping of the LTTE units. On first week of June troops managed gain control over entire zone and captured large amount of arms left by LTTE. The military intelligence disclosed the LTTE leader Prabakaran along with Sea Tiger leader Colonel Soosai narrowly escaped from advancing troops.

Though the second stage of this operation was launched on June 3, 1987, to capture the city of Jaffna, the military was forced to abandon it, when Indian Aircrafts escorted by fighter aircrafts infiltrated Sri Lankan air space and dropped supplies for the LTTE in the Jaffna area on June 4. Subsequently Indian Forces landed in Sri Lanka on the 26th of June with the signing of Indo-Lanka Accord.