In 1971, he was promoted to the rank of Lieutenant Colonel in the Ceylon Army Volunteer Force and was appointed commanding officer of the Field Security Detachment, which was tasked with internal security. 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. On 5 April 1971, the JVP attacked several police stations in a premature start to its planned insurrection. 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. Field Security Detachment was tasked with the security of the Prime Minister and Temple Trees. Ratwatte retired the Army in the late 1970s.