An informal ritual substituted for Roman Catholic processions that were prohibited in Protestant strongholds in the Netherlands. While Catholics could not formally process, there was no law against a group simply walking together in the street, and no one could stop them from silently praying as they walked.
A dying man was given Holy Communion by a priest on a sick call. The man vomited, losing the Holy Sacrament. The Host was then put in the fire. It miraculously remained intact, and was recovered from the fire in one piece harm to It or the person retreiving It.
This miracle was officially recognised the Church, a chapel was built where the house had stood, and pilgrimage route established to it.