[7] After Sayidiman finished his final exam, he was deployed to Surakarta on 19 September 1948 to quell the Madiun Affair.

[8] The company was initially deployed in Surakarta, but was transferred to Wonogiri after the Nasuhi Battalion—the main battalion of the company—faced heavy resistance from the People's Democratic Front troops.

Sayidiman did not hold his old post for a long period as in December 1949 he was transferred to command the 1st company inside the 13th Brigade in an acting capacity.

After the peace treaty between Indonesia and the Dutch was signed, Sayidiman was promoted to first lieutenant on 12 April 1950 and became the company's commander.

Following a reorganization inside the 13th Brigade, Sayidiman was transferred to the 2nd Company in the battalion in June 1950, where he fought against the Darul Islam rebels.

[13] According to Salim Said, a lecturer in the Indonesian Defence University, Sayidiman initially wanted to attend military schools abroad after the peace treaty was made but changed his mind because he felt that he "owed a debt of gratitude to the people".

[16] Sayidiman was promoted to lieutenant colonel and his battalion was deployed to fought against the Revolutionary Government of the Republic of Indonesia (PRRI) in North Sumatra.

On 18 October 1958, the battalion departed from the Tanjung Priok Harbor for Sibolga, one of the main base of the PRRI forces.

Sayidiman later expanded the battalion's offensive scope and occupied Kuta Rampak village and Aek Raisan bridge.

[18] After his deployment in North Sumatra, Sayidiman was promoted to major and was posted to the Indonesian Military Academy.

Sayidiman was promoted to Lieutenant Colonel and was transferred to Jakarta to serve in the Indonesian Army Headquarters.

[22] Under his command, the military region launched Operation Lighting (Operasi Kilat) to exterminate communists rebels who sided with the 30 September movement.

[23] The operation resulted in the execution of Marcus Girat, the leader of communist guerilla groups in the Eastern Indonesia region and the arrest of Muhammad Kasim,[23] the incumbent regent of Buton who was accused of being involved in the movement.

Sayidiman visited Irian Jaya (now Papua) and South Sulawesi in June 1973 as part of a working trip.

Sayidiman was promoted to Lieutenant General on 1 December 1973; he attended the First Japanese Indonesian Conference in 1973 on the same month.

Maraden Panggabean, the commander of the armed forces, revealed that Suharto, the president himself, directly ordered the dismissal of Sayidiman.

[35] Sayidiman had a chance to ask about his dismissal when he was about to conduct a report of duty as the Governor of the National Resilience Institute to President Suharto.

[14] Three days after he was dismissed from the army, Sayidiman was appointed as the Governor of the National Resilience Institute, replacing his former superior R.A.

[41] Sayidiman also published the first book about Japan in the Indonesian language, titled Japanese People and Society in the Struggle for Life (Manusia dan Masyarakat Jepang dalam Perjuangan Hidup).

Sayidiman served as the advisor for defence affairs to the Minister of Research and Technology B. J. Habibie and as the chief director of the State Plantation Company XXIV/XXV in East Java.

Suharto, who had to deal with diplomacy at a wider level, appointed four ambassadors-at-large to assist him in his task as a chairman.

[45] In 1993, Sayidiman, along with the ambassador to Ethiopia, Dadang Sukandar was invited by the Provisional Government of Eritrea to observe the Eritrean independence referendum.

Beyond their expectations, Sayidiman demanded Suharto to resign from the presidency as soon as possible and refuse to serve his sixth five-year term.

Sayidiman, along with other retired military officers, viewed the dual function as inefficient and failing to either defend Suharto or resolve prevalent regional conflicts in Aceh, East Timor, and Papua.

Habibie conducted various political reformations, including replacing pro-Suharto members from the Groups Delegation fraction in the People's Consultative Assembly.

In accordance to Javanese customs at that time, married men with a mononym could choose a last name, known as nama tua.

[4] The marriage resulted in five children, namely Adwin Haryanto, Laksmi Adriyani, Umi Riyanti, Adri Sarosa, and Diana Lestari.

[57] Agus Widjojo, who was regarded as one of the armed forces leading intellectuals,[58] stated that "Sayidiman's train of thought has no end station.

"[c] Suryo Prabowo, former chief of staff of the armed forces, described Sayidiman as a "plenary professional soldier, diplomat, thinker, and educator who is still active writing books and journal until the end of his life".