Saint Peter Canisius (1521-1597) was born in Nijmegen, which at present is in the Netherlands but at the time was part of the diocese of Cologne in Germany. His father, a wealthy merchant, was burgomaster of the city. When Peter turned fifteen, he was sent to study at the University of Cologne. There, he met Blessed Peter Faber, one of the founders of the Society of Jesus (Jesuits). He made the Spiritual Exercises under his direction and soon thereafter joined the Jesuit Order. He was ordained a priest in 1546.
Saint Peter Canisius lived during the outset of the Lutheran heresy in Germany, and spent his life combating it. He approached the Holy Roman Emperor about the archbishop of his diocese, Hermann von Wied, who had secretly gone over to the Lutherans, and obtained his deposition, saving the Catholic Church in the Rhineland from serious harm. He fought for the dismissal of the court preacher Phauser, who also had accepted Protestant beliefs and was cohabiting with a woman. He spoke and wrote to the emperor about him, and debated him in person, eventually obtaining his dismissal. He travelled much and wrote extensively in defence of the orthodoxy of the Catholic faith. Some of his works include the history books The History of John the Baptist and The Incomparable Virgin Mary, both written as a reply to Magdeburg Centuries, a protestant church history which is a large-scale attack on the Catholic Church.
In 1584, Saint Peter had a mystical experience which convinced him that he should cease his travels and remain in Switzerland for the rest of his life. He spent his last years building up the Church in Fribourg through his preaching, teaching, and writing. He suffered a near-fatal stroke in 1591 but recovered and continued as an author for six years. Saint Peter Canisius died on December 21, 1597 and was canonised and declared a Doctor of the Church in 1925 by Pope Pius XI. He is considered the second apostle to Germany (Saint Boniface, from England, being the first).