Trí was born in Bình Tuoc, Biên Hòa, Đồng Nai Province, French Indochina, just northeast of Saigon.

After entering the French colonial forces in 1947, he graduated from Do Huu Vi Officer Class and the following year was sent to Auvour, France to attend infantry school.

[4][5] At 13:00 on 3 June, some 1,500 protestors attempted to march towards the Từ Đàm Pagoda in Huế for a rally, having gathered at Bến Ngự bridge near the Perfume River.

[4][5] At 18:30, military personnel at the scene dispersed the crowd by emptying vials of brownish-red liquid on the heads of praying protestors, resulting in 67 Buddhists being hospitalised for chemical injuries.

At the Từ Đàm Pagoda,[9] which was the base of leading Buddhist activist leader, Thích Trí Quang,[10] Monks tried to cremate as per their custom the coffin of their colleague who had self-immolated.

As troops attempted to erect a barricade across the bridge leading to the pagoda, the crowd fought the heavily armed military personnel with rocks, sticks and their bare fists, throwing back the tear gas grenades that were aimed at them.

Seventeen of the 47 professors at Huế University, who had resigned earlier in the week in protest after the firing of the school's rector, Father Cao Văn Luân,[12] a Catholic priest and opponent of Diệm's brother Archbishop Pierre Martin Ngô Đình Thục, were also arrested.

[9] Despite his vigorous application of Diệm's military policies against Buddhists in central Vietnam, where in the words of Ellen Hammer, Trí "ruled...with an iron hand", he was still involved in plotting against the regime even before the attacks on the pagodas.

As a result, the Diệm loyalists were stuck in a meeting room and were unable to mobilize the Republican Youth and other Ngô family paramilitary and activist groups.

Trí could only promise safe passage on an American plane to the capital, where embassy officials would meet Cẩn[15] who wanted asylum in Japan.

[20] Thiệu's regime became more pro-active,[21] declaring martial law,[22] widening conscription,[22] and organising token anti-corruption campaigns were carried out.

[23] Thiệu used the threat of the Việt Cộng to increase his political power,[24] arresting, exiling or relieving senior officers who supported Kỳ.

[25][26] Thiệu recalled Trí from South Korea and made him Commander of III Corps, which surrounded the capital Saigon and was crucial in blocking or orchestrating coups.

Thiệu gave orders directly to his supporters in senior positions, bypassing Trí's own superior, Cao Văn Viên.

He was known for his flamboyant style, wearing a camouflage jungle suit, a black three-starred cap to indicate his rank, carrying a snub-nosed Smith & Wesson .38 handgun, and was always seen with a swagger stick, quipping "I use it to spank the Viet Cong".

As a lieutenant general, he performed brilliantly as commander of III Corps during the 1970 Cambodian Campaign, earning a laudatory sobriquet from the United States news media as "the Patton of the Parrot's Beak".

[1] In late February 1971 Trí was ordered north to take command of beleaguered I Corps forces after Operation Lam Son 719, a 1971 incursion into Laos, had gone astray due to the incompetent leadership of Lieutenant General Hoàng Xuân Lãm.