In 1919, Father Eustace was ordained a priest. In the following years, he served the Dutch people in various missions, distinguishing himself through his missionary work done with love and steadfastness.

The following year, the priest took up work in a colony of Belgian glaziers who, since the First World War, had settled in Maassluis, a small North Sea port near Rotterdam. He was appointed the first chaplain of the place, a difficult appointment since he had served alone among the Walloons.

In his first few days there, Father Eustáquio realized he was in a place where people lived without God and without morals. The Blessed's work was arduous, and it was there that his ministry dedicated to caring for the sick and suffering began.

The Blessed One's firmness and love for his neighbor earned him the trust of the people living in the colony, and in a short time the situation there changed. Father Eustáquio's dedication and zeal for the community led King Albert I of Belgium (1875-1934) to award him the title of "Knight of the Belgian Crown".

In the book, "The Vicar of Poá," Father Venâncio describes some of the work of Blessed Father Eustáquio while he was in the colony of Belgian glaziers:

“"He devoted special attention to children, organizing a school for them. He sent letter after letter to both the Dutch and Belgian governments, requesting social assistance. He pestered embassies and consular authorities with visits, seeking to secure a domestic school for girls, a sewing class for young women, and an entertainment venue or patronage for young men, so they wouldn't spend their nights in taverns."”