The city was occupied by forces of the French Revolution, and Triest continued pastoral work while spending much of the next five years in hiding, and traveling in disguise.

Both congregations undertook the care of the mentally ill housed in the crypts of Devil's Castle, an old fortress built to guard the port.

[1] Triest sent a small group of brothers to Froidmont to work at the psychiatric hospital of Saint Charles.

The rules he wrote for his congregations joined contemplation to active service and show a distinct Cistercian influence.

With the departure of the Alexian Brothers, who made home visits to the sick and buried the dead, city officials asked Triest to establish another congregation to fill the need.

In 1823 he founded the Congregation of the Brothers of Saint John of God to provide homecare; and in 1835, the Sisters of the Childhood of Jesus to care for foundlings.

in 2001 the Process for the Beatification of the Servant of God Peter Joseph Triest was solemnly opened on 26 August in Ghent Cathedral.