He fought with courage in the face of an enemy attack, sacrificing his life so as to enable his troops of his platoon to withdraw with their injured.

After completing his training at the Sri Lanka Military Academy, he was commissioned as a Second Lieutenant in the 3rd Battalion, Gajaba Regiment.

Then with the enemy advancing towards his position, 2nd Lt Nissanka ordered the surviving members of his platoon to withdraw with their wounded.

[citation needed] For this heroic deed 2nd Lt Nissanka was posthumously honoured with the Parama Weera Vibhushanaya medal in 1996.

[citation needed] "It is recommended that 0/61672 2/Lt KWT Nissanka of the Gajaba Regiment, be awarded the Parama Weera Vibushanaya as a reward for his individual acts of gallantry and conspicuous bravery of the most exceptional order in the face of the enemy, performed voluntarily whilst on active service and with no regard to the risks to his own life and security with the objective of safeguarding thereby, the lives of his comrades or facilitating the operational aim of his force,"