Due to his political connections with President Nguyễn Văn Thiệu, he was still serving as I Corps commander when the North Vietnamese launched the Easter Offensive in 1972.

The situation for the South Vietnamese in Military Region 1 had regained some stability after the defeat of a three-division PAVN push during late 1974.

At a meeting in Saigon on 13 March President Thiệu was briefed on the military situation by Trưởng and another corps commander.

The general had developed two contingency plans: The first was predicated on government control of Highway 1, which would be utilized for two simultaneous withdrawals from Huế and Chu Lai to Da Nang; The second course presupposed PAVN interdiction of the highway and called for a withdrawal into three enclaves: Huế, Da Nang, and Chu Lai.

The president then stunned the general by announcing that he had misinterpreted his previous orders:[4] The old imperial capital of Huế was not to be abandoned.