In spite of opposition he gained many converts. He spent much time at the foot of the altar or before his crucifix preparing himself for the martyrdom of which he had a premonition. In April 24, 1622, he made his confession, said Mass, and preached at Gruch. At the end of his sermon he seemed to be in ecstacy and foretold his death to several persons.
From Gruch he went to Sevis where he was fired upon by a Calvinist but was not injured. On his way back to Gruch he met twenty Calvinist soldiers with a minister at their head. They called him a false prophet and urged him to embrace Calvinism. He replied, "The Catholic religion is the Faith of all ages; I fear not death." He received a blow upon his head, arose upon his knees, prayed for his persecutors and with the name of Jesus and Mary on his lips, he received the death-stroke.
His feast day is April 24th.
Saint Fidelis was born in 1577 at Sigmaringen, a town in the principality of Hohenzollern. In 1612 he received Holy Orders and soon afterward entered the Capuchin Order at Fribourg. He changed his baptismal name Mark to Fidelis. At the request of the Congregation of Propaganda he and eight Fathers of his Order undertook the mission among the Calvinists in the Canton of the Grisons in Switzerland.