He worked as a civil servant for some time, and joined the PETA military organization during the Japanese occupation of the Dutch East Indies, rising to become a battalion commander.

After the proclamation of Indonesian independence, he organized a unit in the nascent BKR and later rose to the rank of a divisional commander, approving the General Offensive of 1 March 1949.

He resigned in 1955, and during his ensuing diplomatic career attempted to garner support for Indonesia in the West New Guinea dispute.

[1][2] During the Japanese occupation of the Dutch East Indies, Soegeng joined the Japanese-founded Defenders of the Homeland (PETA), where he was part of the 2nd battalion, based in Magelang, as a company commander.

He was the superior officer of Suharto at the time, and Soegeng gave approval to the General Offensive of 1 March 1949, which resulted in a significant Indonesian political victory.

[9] During the 17 October affair in 1952, Soegeng was on sick leave, and a power struggle occurred between his subordinates which resulted in the temporary acting commander, Lt. Col. Suwondho, being arrested and dismissed.

[10] Soegeng, who was at the time still inactive yet considered a politically moderate and competent officer, was appointed acting Chief of Staff of the Indonesian Army on 15 December 1952 replacing Abdul Haris Nasution.

[11] Due to his illness during the coup attempt, he was seen as uninvolved in the incident, and he was considered as an acceptable compromise replacement for Nasution.

[8] The early weeks of his tenure saw a clash with the politicians in Jakarta, when he attempted to appoint Joop Warouw as the regional commander for East Indonesia.

[15] Soegeng once again threatened to resign in December 1953, when the Defense Minister at the time, Iwa Kusumasumantri, made several controversial appointments to the Army General Staff.