He gained a commission as a volunteer officer in the rank of second lieutenant in the 2nd (V) Battalion, Ceylon Sinha Regiment (2CSR) based in Kandy under the command of Colonel S. D. Ratwatte.

Prime Minister Sirima Bandaranaike was worried of a possible threat to the government from army officers loyal to the opposition political parties with her prior experience in the 1962 attempted coup d'état.

Captain Denzil Kobbekaduwa, under Ratwatte's command reported a potential threat to the government by the Janatha Vimukthi Peramuna (JVP) which was preparing for an armed revolt.

That evening, after police captured a group of JVP members who were planning to kidnap Prime Minister Bandaranaike from her private residence, Major General Sepala Attygalle and Lieutenant Colonel Ratwatte briefed Bandaranaike and escorted her to the Prime Minister's official residence Temple Trees, which became the operations center coordinating the counter-insurgency activity of the Ceylonese government.

[3][5][6][7] In February 1989, he entered parliament having been appointed to it by the National List from the Sri Lanka Freedom Party and sat in the opposition.

De Silva was overruled and planning commenced under Major General Rohan Daluwatte for Operation Riviresa.

Launched in late 1995, Operation Riviresa under Daluwatte recapture of the Jaffna peninsula, but failed to cut off LTTE units that withdrew to the jungles of Wanni.

The recapture of Jaffna was well celebrated and Ratwatte who oversaw it as deputy defence minister; was promoted to the rank of general by President Chandrika Kumaratunga in 1995 and was awarded the Riviresa Campaign Services Medal.

This led to his falling out of favour with President Kumaratunga, who established the post of Chief of the Defence Staff to reduce Ratwatte's influence over the operational matters of the military.