Few people knew General Hieu held the position of 1st Infantry Division Acting Commander for a short time, less than three weeks, from end November 1963 to December 12 1963. It was Lieutenant Colonel Duong Dien Nghi who revealed this fact in his speech delivered during the book presentation in San Jose on April 23, 2005:
The implementation of the action plan succeeded in forcing the protestors into retreat. The situation seemed calm by 9/1963; and Colonel Tri was promoted to Major General as a result. However, approximately two months later, on 11/1, a major event occurred. President Ngo Dinh Diem and his brother were assassinated. The Military Junta governed the country. Hue Buddhists seized the opportunity to claim credit in the overthrow of Diem regime, and attacked main players in the 1st Division; those they called “oppressors of Buddhists”. Once again, I had to deal with the situation. The Central Government added another assignment to my portfolio: Director of Hue Radio Broadcasting Station.
The Central Directorate of General Officers promoted General Do Cao Tri to Lieutenant General. Major Hieu, Chief of Staff, was promoted to Lieutenant Colonel; Captain Ton That Khien, G3 Head, to Major; and I, Lieutenant to Captain.
Lieutenant General Do Cao Tri went to Saigon to meet with the Directorate of General Officers. At the Division, LTC Hieu unbuttoned his Major insignia from his shirt and buttoned it onto Ton That Khien. Ton That Khien unbuttoned his Captain insignia and buttoned it onto me. We all did not feel happy getting these new grades that were rather belated. LTC Hieu remained pensive. Major Khien and I, we were thinking about the drama of the 1st Republic of Vietnam, about its fall and felt sad for President Ngo Dinh Diem and his advisor Ngo Dinh Nhu. Hue University’s students and Buddhists still focused on us with their accusations; in particular me, the most vehement oppressor of Buddhists although I had not resort to force and violence tactics. I again had to deal with those thorny and complex innuendos; nevertheless, I had gained unforgettable numerous beneficial lessons.
Despite the fact the Revolutionary Central Committee had taken hold of the government, the situation in Hue still seemed to be unstable; and when Lieutenant General Do Cao Tri was ordered to take over the I Corps Command in replacement of General Le Van Nghiem, he requested that LTC Hieu be promoted to Colonel and appointed 1st Infantry Division Acting Commander and Major Khien to LTC and 1st Infantry Division Chief of Staff. This special promotion took place around three weeks after the military coup.
Colonel Hieu took over the command of 1st Infantry Division. While he was reorganizing the unit, an order was issued swapping the positions of General Nguyen Khanh and General Do Cao Tri. General Do Cao Tri took over II Corps Command and Colonel Hieu followed him to hold the position of II Corps Chief of Staff. Colonel Tran Thanh Phong, I Corps Chief of Staff, became 1st Infantry Division Commander.