[1] He was a supporter of the Đại Việt Quốc Dân Đảng (DVQDD, Nationalist Party of Greater Vietnam), a Roman Catholic political movement.

After becoming a major general in 1956 and commanding the Airborne Brigade, Đức served for a year as ambassador to South Korea.

Đức used his experience of France to draft fake documents purporting to show the junta of Dương Văn Minh wanting to go along with the French proposal.

In 1955, during the transition period after the partition of Vietnam, Đức was a VNA colonel and fought in operations against the Hòa Hảo warlord Ba Cụt, who was trying to wrest power from Prime Minister Ngô Đình Diệm.

At the time, there was a coup plot against the ruling junta of General Dương Văn Minh, and Đức was recruited by a group including Khánh, Đỗ Mậu and Trần Thiện Khiêm.

[6] At the time, the French President Charles de Gaulle wanted Vietnam to become a neutralist country, with the Americans out of the region.

They purported to show that three prominent members of the junta: Generals Minh, Kim and Trần Văn Đôn had been bought by French agents and were on the brink of declaring South Vietnam's neutrality and sign a peace deal to end the war with the North.

At 15:00 the next day, Khánh took over the Joint General Staff Headquarters and seized power in a bloodless coup, having caught the junta off guard.

Duc served as the commander of IV Corps,[9] which oversaw the Mekong Delta region of the country, from 4 March until 15 September 1964, when he was replaced by Major General Nguyễn Văn Thiệu.

[9] The removal was due to Buddhist lobbying, who accused Khánh of accommodating too many Catholics regarded as Diệm supporters in leadership positions.

[4] Another member of the conspiracy was Colonel Phạm Ngọc Thảo, who, while ostensibly a Catholic, was actually a communist spy trying to maximize infighting whenever possible.

Four battalions of rebel troops moved before dawn from the Mekong Delta towards Saigon, with armored personnel carriers and jeeps carrying machine guns.

[4] However, Phát and Đức could not apprehend Khánh, who had escaped the capital and flew to the central highlands resort town of Đà Lạt.

After talking to Phát and Đức, they concluded the same and decided to back the incumbent, publicly releasing a statement through the embassy endorsing Khánh.

[21] According to an anonymous source, Phát's hardline Diệmist public statements and radio broadcast comments had caused Đức to reconsider his own participation in the coup.

Kỳ claimed Khánh was in complete control and that the senior officers involved in the stand-off, including Đức, "agreed to rejoin their units to fight the Communists".

Phát's lawyers started by moving for the charges against the conspirators to be dismissed, claiming the rebels had not been captured "red-handed"; this motion was denied.

[24] Đức claimed he had decided to end what he regarded as a military protest demonstration when Khánh promised to consider his concerns, and then returned to the IV Corps headquarters in the Mekong Delta.

Most observers thought the suspicions against the arrested men were not credible, and Đức was released after 24 hours and given an informal warning to avoid political activities.

Kỳ made a speech denouncing the alleged coup plot without naming individuals the military was placed on a higher level of alert.