He was born on November 20, 1785 near Kamnik in the Austrian province of Carniola, (now Slovenia). The Slovenian form of his family name was Pirc, but in the United States he used the spelling Pierz. Little is known of his parentage and early life.
He received education in the gymnasium and the diocesan seminary in Laibach.
He was ordained in 1813 and served successively thereafter three local parishes. At the solicitation of a missionary among the Chippewa Indians, Pierz set out in 1835 for the United States as a missionary supported mainly by the Leopoldinen-Stiftung, a Viennese board of missions. His work for many years was with the Indians and settlers about the mission at Arbre Croche, now Harbor Springs, Michigan.
Prior to 1839, however, he served at Sault Ste. Marie and established important stations on Lake Superior. He was particularly successful in inducing the Indians to become an agricultural people. In 1852 he departed for the upper Mississippi, a large field hitherto neglected by his church. Despite his advanced age he traveled hundreds of miles every year to visit bands of Chippewa.
His published reports were successful now, as his earlier letters from Michigan had been, in interesting Catholic Europe in the Indians and thus in providing funds for his work. When the Sioux rose against the whites in 1862, his influence helped to keep the Chippewa from rising also. With the aid of assistants whom he secured in Europe in 1863 he continued to labor among the Indians until 1871.
Perceiving that white men would inevitably settle close to his Indians, he determined to see that they were German Catholics. Accordingly he sent out a prospectus and published many letters describing central Minnesota in terms calculated to attract this class. The prospectus appeared in his Die Indianer in Nord-Amerika, and together with his letters, printed in many European and American periodicals, brought great numbers of Germans to central Minnesota.
In 1873 he returned to his native land, where he died.
There is no information about his marital status.
