Lady Chapel: The Miracle of Empel or the Battle of Empel is an event in December 1585 during the Eighty Years' War in which 4000 Spanish soldiers escaped destruction by State troops in the vicinity of Old Empel.
The Spanish troops were trapped in the cold and rain for five days, enclosed between the States troops with their ships on the water. The gunners on the ships fired continuously at the Spanish positions from 4 to 7 December. To protect themselves against the impending landing of the States, the tercios dug in around the church of Empel. A Spanish soldier found an undamaged painting depicting the Immaculate Conception of Mary. Bobadilla had the image placed in the church, after which a prayer took place.
December 8 was the day on which the Immaculate Conception had been traditionally celebrated for several centuries, and the Bossche Lady-brotherhood held a solemn procession to implore God's help.
Source and more info: Wikipedia