He led Indian Air Force during the India-Pakistan War in the year 1965. For his active commanding skills during India-Pakistan War of 1965, he was awarded the ‘Padma Vibhushan’. In the very next year, in 1966, he became the first Indian Air Force Officer gets promoted to ‘Air Chief Marshal’.

He retired from the Air Force while serving the post of Air Chief Marshal on January 15, 1966. After that, he was very active as a Diplomat, Politician, and Advisor of the Indian Government. He was appointed as the Indian Ambassador to Switzerland and the Vatican simultaneously in the year 1971. Later from 1974 to 1977, he was appointed as the ‘High Commissioner to Kenya’. From 1989 to 1990, he served as the Lieutenant Governor of Delhi. Then, in January 2002, he was appointed as the “Marshal of the Air Force”. This made him promoted to five-star rank and became the first and only officer of Indian Air Force to rank as the Marshal of the Air Force. It is equal to Army Rank of ‘Field Marshal’.

Excluding him, the only two officers promoted to five-star rank are Field Marshals Sam Manekshaw and K. M. Cariappa of the Army.

He died at the age of 98 years, on September 16, 2017, due to Cardiac Arrest. He was the oldest serving military officer in the Country. His last rites ceremony was felicitated with the honor and was accorded a 17-gun salute. His last rites ceremony was attended by many dignitaries. Whereas, before his death PM Narendra Modi, Defence Minister Nirmala Sitharaman, and the three service chiefs of Army, Air Force, and Navy visited Marshal Arjan Singh in the hospital.