Based in the former imperial capital of Huế, Cẩn operated private armies and secret police that controlled the central region and earned himself a reputation as the most oppressive of the Ngô brothers.

Cẩn, who succeeded in eliminating alternative nationalist opposition in central Vietnam, became the warlord of the region when his brother became president of the southern half of the partitioned nation in 1955.

Thục overshadowed Cẩn and aggressively promoted Catholicism, which led to the banning of the Buddhist flag in 1963 during Vesak, the celebration of the birthday of Gautama Buddha.

Cẩn had been offered asylum by the US Department of State, but ambassador Henry Cabot Lodge Jr. had CIA officer Lucien Conein arrest the fallen Ngô in Saigon.

Cẩn was the fifth of six sons born to Ngô Đình Khả, who was a mandarin in the imperial court of Emperor Thành Thái, who was ruling under French control.

At the end of the war, the Japanese left the country, and France, severely weakened by political turmoil within the Vichy regime, was unable to exert control.

Cẩn accumulated great wealth through corrupt practices such as graft in awarding foreign aid contracts from the United States governments of Dwight D. Eisenhower and John F. Kennedy to Vietnamese businessmen.

He required the businessmen to pay a fee to the National Revolutionary Movement – the official party of the regime[19] – in return for the processing of applications for foreign aid contracts and import licenses.

Cẩn was widely believed to be selling rice to North Vietnam on the black market, as well as organising the trafficking of opium throughout Asia via Laos, and monopolising the cinnamon trade.

[20] Comparing Cẩn to his brothers, Scigliano said that he was "also considered the most severe, some would say primitive, member of the family and he rules his domain with a strict and sometimes brutal hand".

[17] Referring to his autocratic style, a Vietnamese critic said that unlike Diệm, Cẩn was consistent and left his followers in no doubt as to what he wanted: "They are not confused by double talk about democratic ideals and institutions".

[24] In spite of his autocracy and iron rule, Cẩn earned praise from Huế-based US officials for his relatively high levels of success against the Cong san insurgency.

[1] The Popular Force was an alternative to the Strategic Hamlet Program which was used on a much larger scale in the south by Nhu, who moved peasants into fortified camps in an attempt to isolate Viet Cong cadres from accessing the rural populace and intimidating or otherwise gaining their support.

[23] Cẩn believed the United States, whose relations with South Vietnam had become strained, caused an explosion during the Vesak shootings, to destabilise his family's regime.

To deal with the tenacious fish, they called in the Army of the Republic of Vietnam Special Forces, led by Colonel Lê Quang Tung under the direction of Nhu.

Army of the Republic of Vietnam (ARVN) helicopters began landing at the site, with paratroopers filling their bottles with water that they believed to be magical.

[20][30] The protests were met with brutal crackdowns, including ARVN Special Forces attacks on Buddhist pagodas which left hundreds missing, presumed dead.

Following the downfall of the Ngô family, the White House came under pressure from the South Vietnamese public to take a hard line against Cẩn.

Although junta member General Trần Văn Đôn asserted that the compound predated the Diệm era, the town's citizens saw Cẩn as a mass murderer.

On 4 November, two days after the coup ended, thousands of irate townspeople walked three kilometres to Cẩn's house on the city's southern outskirts – where he lived with his aged mother – demanding vengeance.

[35] The US State Department was faced with a dilemma: sheltering Cẩn would associate them with the protection of a corrupt and authoritarian regime that had tortured and killed thousands of its own people.

General Đỗ Cao Trí, the commander of the ARVN I Corps, who had repressed the Buddhists in Huế, privately told Cẩn that the junta would allow him safe passage out of Vietnam.

Instead of sending embassy officials to Tân Sơn Nhứt airport, Lodge sent CIA officer Lucien Conein, who had helped the Vietnamese generals to plan the coup.

[35] Cẩn's case was damaged by the release of tens of thousands of political prisoners, who recounted tales of torture at the hands of the Ngô brothers.

[36] It was reported that General Nguyễn Khánh – who had deposed Minh in a January 1964 coup – offered Cẩn exile if he handed over his foreign bank deposits.

[38][39] Despite having helped to arrest Cẩn, Lodge advised Khánh to be restrained in his handling of the case for fear of stoking religious resentment or upsetting international opinion with a death penalty.

This placed Minh – who was still the titular head of state – in the position of approving a third death in the Ngô family, having already ordered his bodyguard Nguyễn Văn Nhung to execute Diệm and Nhu during the coup.

Cao Văn Luân, Catholic rector of Huế University who had been fired for falling afoul of the powerful Archbishop Thục, asked Lodge that Cẩn not be executed.