De Silva joined the Sri Lanka Army as an
officer cadet in February 1980 and received his basic training at the
Sri Lanka Military Academy. He was commissioned as a
second lieutenant in the 1st Field Engineer Regiment,
Sri Lanka Engineers in 1981. He gained promotion to the ranks of
captain in 1985,
major 1989),
lieutenant colonel (1994),
colonel (1997),
brigadier (2003) and
major general in November 2009. He went on to command the 6th Field Engineer Regiment and had served as the
brigade commander of the Engineer Brigade, the 51-2 Infantry Brigade and the 56-2 Infantry Brigade. He had served as the commandant of the
Sri Lanka School of Military Engineering, the
Defence Services Command and Staff College and the
Sri Lanka Military Academy. His commands include Commander Forward Maintenance Area,
Wanni;
Security Forces Headquarters – Kilinochchi and in the Sri Lanka Army
General Staff, he had served as additional military secretary, director plans,
military secretary and director operations. He had served as
colonel commandant of the
Corps of Sri Lanka Engineers and was a member of military delegations to Malaysia and China. He served as commander of the
Sri Lanka Army Volunteer Force (SLAVF) before taking up appointment in 2013 as Chief of Staff of the Sri Lanka Army. In 2014, he was appointed
deputy chief of mission in the
Sri Lankan embassy in Moscow. In February 2015, he was appointed
Commander of the Army and promoted to the rank of
lieutenant general. In June 2017 he was promoted to the rank of
general and appointed
Chief of Defence Staff and served till August 2017. He graduated from
Staff College, Camberley, and the Nanjing PLA Army Command College. He has attended the bomb disposal course at the
College of Military Engineering, Pune, the Engineer Company Commanders' Course at the
Military College of Engineering, Pakistan, the Higher Command Course at the
Army War College, Mhow, and the Advanced Security Cooperation Executive Course at the
Asia-Pacific Center for Security Studies. ==Later work==