The Battle of Pampeluna (also spelled Pamplona) occurred on May 20, 1521, during the Italian War of 1521.
It was at this battle that Inigo Lopez de Loyola, better known as St. Ignatius Loyola, suffered severe injuries, a French cannonball shattering his leg. His meditations during his long recovery set him on the road of a conversion of life from soldier to priest. He would eventually found the Society of Jesus (the Jesuits), and create the Spiritual Exercises, which is the basis for the idea of "retreats" as an experience of prayer as practiced in the Roman Catholic Church.