St. Fidelis of Sigmaringen was a Catholic priest and martyr who lived in the 17th century. He was born in 1577 in Sigmaringen, a town in present-day Germany, and was named Mark Rey. After completing his studies in law and philosophy at the University of Freiburg, he became a lawyer and began practising in Colmar, France.
However, after a few years of practising law, Mark Rey decided to become a priest and entered the Capuchin order, taking the name Fidelis. He was ordained a priest in 1612 and spent the next few years preaching and evangelizing in Switzerland and Germany, where he earned a reputation for his eloquence and his ability to convert Protestants to Catholicism.
In 1622, during the Thirty Years’ War, Fidelis was sent to preach in the territory of the Protestant city of Grisons, in Switzerland. There, he faced opposition from the local Calvinists, who were hostile to the Catholic Church. Despite this, Fidelis continued to preach and evangelize and was able to convert many people to Catholicism.
However, his success and his strong defence of Catholicism made him a target for the Calvinists. On April 24, 1622, while returning from a preaching mission in Seewis, Fidelis was attacked and killed by a group of Calvinist soldiers.