He was suspended following an alleged Ceylonese coup d'état attempt in 1966 and was reinstated in 1970, attached to internal security prior to and during the 1971 Insurrection.

Thereafter, he was attached to the newly formed Army's Field Security Detachment under the command of the recently promoted Lieutenant Colonel Anuruddha Ratwatte.

The Field Security Detachment was tasked with identifying internal threats to and safeguarding the prime minister, following Bandaranaike's experience in the 1962 attempted coup d'état.

Based on investigations by the military police unit under his command, Kobbekaduwa warned the government that a youth insurrection was imminent.

The warnings materialized when the JVP insurrection started on 5 April 1971, taking the government and the military unprepared in its scale and magnitude.

During his posting he was able to gain a good understanding of the Jaffna Peninsula during the onset of the Tamil militancy that led to the Sri Lankan Civil War.

In April 1981, he was promoted to the rank of lieutenant colonel and the following year he was transferred to Army Headquarters as the general staff officer (Grade 1) of G branch.

It was the largest formation deployed by the Sri Lankan Army at that point and the first conventional battle to take place in the civil war.

By the end of the first week of June, the army had gained control over the entire zone and captured a large cache of arms left by the LTTE.

[10] President J.R. Jayewardene and Minister of National Security Lalith Athulathmudali had political responsibility for the operation and terminated it following Operation Poomalai, the Indian air force's show of strength, in which it dropped supplies over Jaffna for the besieged Tamil Tigers on 4 June 1987, leading to the Indo-Sri Lanka Accord.

In December 1987, he was appointed Principal staff officer of the Joint Operations Command and was nominated to attended the Royal College of Defence Studies.

On 10 July 1991, Elephant Pass came under siege by an LTTE attack which it code-named "Operation Charles Anthony", its first suicide bomber.

At this point, Major General Kobbekaduwa proposed an amphibious assault launched code named Operation Balavegaya.

After several days of fighting the relief force was able to reach and linkup with the besieged garrison and by 19 August the LTTE militants withdrew.

In the end of August, General Kobbekaduwa launched "Operation Lightning" in the Weli-oya sector to divert pressure on Elephant Pass.

This was when he was preparing for a new offensive to capture the Jaffna peninsula which was under LTTE control, it was code named "Operation Final Count Down".

Since the launching pad for the offensive was the island of Kayts on 7 August, General Kobbekaduwa moved to Karainagar naval base by helicopter with his staff.

He spent much of the night planning the upcoming offensive with Brigadier Vijaya Wimalaratne, Jaffna Brigade Commander and Commodore Mohan Jayamaha.

On 8 August 1992 at 8.00 am the group made up of Maj. General Kobbekaduwa, Brigadier Wimalaratne and Commodore Jayamaha along with several other officers headed out on a naval patrol boat towards Jaffna and returned to Kayts pier.

Half way the general order that they all use one vehicle as to not to attract fire from LTTE units in the Jaffna peninsula which was only one-half kilometer away.

The two wounded officers were rushed to the helicopter waiting to transport the group to base, which took them to the military hospital in Plalay where Commodore Jayamaha was found dead on arrival.

[14] On the day of his military funeral, a crowd numbering about 100,000 persons descended on the Colombo general cemetery, chanting anti-government slogans and throwing stones at government ministers.

Following her election to office, President Chandrika Kumaratunga, appointed a Presidential Commission of Inquiry, made up of Tissa Dias Bandaranayake (Chair), Justice D. P. S. Gunasekera and Gamini Ameratunga, High Court Judge.

A report from the Criminal Investigation Department found Hathurusinghe's evidence could not be corroborated, yet Bandaranayake allowed her testimony.

[17] Although the validity of Hathurusinghe's evidence was questioned,[18] the Presidential Commission speculated that then President Ranasinghe Premadasa, as well as members of the Sri Lankan Army such as Major W A N M Weerasinghe, were "directly responsible" for his death.