Peter Canisius

Born Pieter Kanis on 8 May 1521 in the Netherlands, he joined the Jesuits and spent decades moving through Germany, Austria, Bohemia, Moravia, Switzerland, and the British Isles—not as a theorist but as an operative, preaching, teaching, and rebuilding institutional Catholic presence where it had collapsed. The restoration of the Catholic Church in Germany is largely credited to the Jesuit campaign he led on the ground. He died on 21 December 1597, and the Church later named him both a saint and a Doctor—a rare title reserved for those whose writing shaped doctrine.