The 12th Battalion of the Sinha Regimentwas formed in September 1996 in Kottamulan, Jaffna and Lieutenant Colonel AP De Z Wickramarathne was appointed as the first Commanding Officer of the Battalion.
This Battalion was deployed in Nelliyadi the Battalion succeeded in countering the activities of the terrorist. It was also successful in killing the leader of the Sea Tigers at the time, Arjun Appa.
On 01st January 1997 Major DC Keppetiwalana RSP psc was appointed as the Commanding Officer of the Battalion.
The Battalion then deployed to Elephant Pass but in April 2000 retreated to Eluththumudduwal.
Major HJ Senevirathne took over command of the Battalion.
Encounters with the enemy caused a rapid decline in the strength of the Battalion thus, the Battalion was amalgamated with the 4th Battalion of the Sri Lanka Sinha Regiment in June 2000.
On 15th October 2007 the terrorists carried out an attack in Thalgasmankada in the Yala National Park. 10 officers and 491 other ranks from the Ambepussa Camp were moved to Hambantota from where they were deployed to Palatupana, Gal Amuna, Kochchipothana, Galge, Dambakele, Weheragala and Warahana with the aim of preventing any further activity by the terrorists. On 22nd October 2007 the Battalion set up camp at Palatupana, Yala.
Troops of the Battalion placed under command to the 572 Brigade took part in an operation to capture the Thampane during the period 23rd December 2007 to 2nd February 2008. On completion of the operation the Battalion had lost (killed) an officer and 5 other rankers. 2 officers and 58 other rankers received injuries. Intercepted radio communication confirmed the casualty figures of the terrorists as 36 killed and 68 injured.
Placed under command to the 572 Brigade the troops of the Battalion were part of the operations conducted from 12th June to 2nd July 2008 aimed at clearing the Mundai and Nadankandal area of terrorist activity. In doing so, the Battalion lost (killed) 4 other rankers while injuries were received by a further 31 other rankers.
Troops on offensive to recapture Nachchikuda Access.
During the period 8th September 2008 and 19th October 2008 the Battalion placed under command to the 571 Brigade, were part of the operation aimed at capturing the strongly built earth bund at Akkarayamkulam in the vicinity of the Kilinochchi Town. The bund constructed by the terrorists to halt the advance of the Army was of a height of 15 - 20 feet while the trench dug on the inner side of the bund was deep and 6 - 7 feet in its width. Troops captured the 1.7km long bund after a fierce battle with the enemy. The Battalion lost (killed) 20 soldiers while 2 officers and 54 soldiers received injuries. The casualty figure of the terrorists was reported to be 87 killed and 113 wounded. This is considered as the fiercest and most difficult to have been won by the Battalion.
Following the success over the enemy, the troops of the Battalion fighting in small groups succeeded in capturing a stretch of 1.7 km of the strongly built earth bund constructed by the enemy at Akkarayamkulam overcoming the challenges posed by booby traps and indirect enemy fire.
