The requirement to have a 'new' Battalion formed arose as with the necessity to have a trained and capable entity for the provision of security to the large reservoirs that were being constructed at the time, commonly termed as 'Mahaweli Projects', as well as the provision of security to the agricultural colonies that were established under the same projects.
Hence, the 5th Battalion of the Sri Lanka Sinha Regiment was formed as part of Sri Lanka Vunteer Force on 1st February 1987.
Its Headquarters was established at No. 666, Galle Road Colombo. The initial strength of the Battalion remained at 30 soldiers and later with the increase of its cadre; both officers and men, the Battalion was deployed to provide security to the Victoria and Kothmale Projects.
Lieutenant Colonel NP Fernando psc SLAC was appointed as the Commanding Officer.
The Battalion underwent Battalion Training at the Maduruoya Army Training School from 23rd November to 17th December 1987 on completion of which the troops were deployed to provide security to the newly established colonies (commonly referred to as Mahaweli Colonies) in Nelumwewa, Nidanwela, Maduruoya and Dimbulagala with its Company Headquarters established at Aralaganwila. The Battalion Headquarters was moved to Maberiyathenna, Digana on 25th December 1987.
On 11th November 1988, Major MGF Mahipala SLAC was appointed as the Commanding Officer.
In addition to the duties relating to the Mahaweli Authority, the insurgency that erupted in the country resulted in the Battalion setting up camps and deploying its personnel in Gampola, Ududumbara, Digana and at the Dakware Estate.
On 30th May 1989, Major WM Kudabanda took over duties as Commanding Officer.
With the sudden demise of Lieutenant Colonel WM Kudabanda on 25th February 1990, Major AMB Amunugama was appointed and assumed duties as the Commanding Officer.
The insurgency causing a great deal of destruction all over the country as well as causing inconvenience to the general public, the Battalion set up detachments and deployed in Kuruwita, Hingula, Bogala, Balawathgama, Wagolla, Dorawaka, Dehiowita, Deraniyagala, Udugumbara, Mahiyangana and Kegalle.
With the insurrection being somewhat controlled and the increase of activity by the separatist terrorist in the North and East of the country, on 23rd June 1990 the Battalion was placed under the 2nd Division. Having established its headquarters in Anuradhapura the troops were deployed on security duties in an area extending from Poonewa to Pomparippu.
On 11th July 1997, a terrorist attack on the detachment at Katupotharesulted in the terrorist over running the camp and also removing the weapons and ammunition from the camp. The Battalion lost (killed) an officer and 10 other ranks.
On 15th February 1993 the Battalion was shifted to Pulmudai. Having established the headquarter at the premises of the Mineral Sand Corporation, detachments were set up at the 10th, 11th, 13th and 14th mileposts, Trinco Junction, Thennamaranwadi, Katupotha, Kokilai, Helambawewa, Padawiya and at Wahalkada.
On 7th June 1997, Major JB Galgamuwa was appointed as the Commanding Officer.
On 26th August 1995 the Battalion moved to Welioya and placed under command to the 6th Brigade. With the headquarter established at Nelumwewa, detachments were set up at Janakapura, Janakapura South, Helambawewa, Thennamaran Wadi, Kethalagama, Kambiliyawa and at the 4th milepost.
The detachment at Halambawewa was attacked by the terrorists on 16th March 1996 resulting in the death of 8 other rankers and injuries inflicted to 7 officers and other rankers. The attackers also removed considerable stocks of weapons and ammunition.
