In 1933, she was sent to the mission hospital in Belgian Congo which her congregation staffed for the colonial government. She contracted tuberculosis and returned to her home country in the summer of 1939, shortly before the start of World War II and the subsequent German invasion of Belgium. Her father was killed shortly after this, causing Sister Xaverine to develop such a hatred toward the Germans that she became involved with the Belgian Resistance. She came to feel that she could not obey the dictates of her faith for forgiveness and applied to the Holy See for a dispensation from her religious vows – a very rare request in her day. She was eventually granted this, and left the congregation on 16 August 1944 from their convent in Uccle.