Son of Guglielmo de Rossi and Elisabetta Masella. He felt an early call to religious life, and was educated by the Friars Minor Conventuals of Brindisi. His father died when the boy was twelve. Studied in Venice. Joined the Capuchin Friars in 1575 at age 16, taking the name Brother Lorenzo. Studied theology, the Bible, French, German, Greek, Spanish, Syriac, and Hebrew at the University of Padua; a brilliant student known for his facility with languages. Priest. Taught theology. Served as linguist andmilitary chaplain. Famous, effective and forceful preacher in any of his several languages. Founded convents of Vienna, Prague, and Graz. Wrote catechisms.
Chaplain of the army of the Holy Roman Empire in 1601. Rallied the German princes to fight a superior Turkish force, and was asked to lead the army into battle at Stuhlweissenburg (modern Albe-Royal) carrying no weapon but a crucifix; the Turks were completely defeated. Master general of his order from1602 to 1605; he was the choice for another term, but turned it down. Carried out important and successful diplomatic peace missions to Munich and Madrid. Assigned in 1605 to evangelize in Germany, where he had great success. Convinced Philip III of Spain to join the German Catholic League. Commissary general of his order for the provinces of Tyrol and Bavaria. Spiritual director of the Bavarian army. Tended to fall into ecstasies when celebrating Mass.
In 1956, the Capuchin Order compiled fifteen volumes of his sermons, letters and writings. Proclaimed Apostolic Doctor of the Church by Pope John XXIIIin 1959.