Even before beginning theological studies Amrhein had become convinced that his vocation lay in the foreign missions.  He felt strongly the desire to become a member of a religious order, and he was profoundly impressed by lectures at Tubingen on the role played during the middle ages by the Benedictine Order in the spread of Christianity and Christian culture.  On Pentecost, 1870 he made a retreat at the recently-founded Benedictine Abbey of Beuron, and six months later he entered the novitiate at Beuron as Frater Andreas.

Although he had from the first shared with Abbot Maurus his missionary hopes, Frater Andreas discovered soon after his monastic profession in 1871 that the contemplative ideals of Beuron did not allow for an active external apostolate.  His attempts to cite medieval precedents for his ideas were seen by his superiors as “temptations to self-will”, and he was given no encouragement.  He was ordained priest in the summer of 1872 and was sent in the fall to Beuron’s fledgling daughter-house of Maredsous.

At Maredsous he met Gerard van Caloen, the later founder of the Abbey of St. Andre’ in Brugge.  The important role each of them would play in implementing the ideal of “Benedictine mission” seems to have appeared in embryo during a pilgrimage to Affligem which they made together in 1878.  They discussed with with each other the idea of founding a missionary institute for Benedictine oblates, but not, it would seem, the possibility of monks actually serving as missionaries.

Recalled to Beuron on account of ill health, Amrhein served his abbey in various capacities during the difficult years of the German Kulturkampf.  He continued to petition his abbot for permission to do work related to the foreign missions; and finally, in 1879 he received Abbot Maurus’ promise that if at the end of three years this was still his (Amrhein’s) desire, he would be permitted to work in some capacity in the missions.  In 1880 Fr. Andreas was sent to Beuron’s foundation at Erdington in England, where he became acquainted with Bishop Herbert Vaughan and the latter’s plans for a missionary society.  With the permission of his abbot Andreas Amrhein became the first member of Mill Hill in 1882⁶; but in the following year Abbot Maurus withdrew his permission and required Amrhein to choose between Mill Hill and Beuron.

Amrhein remained a monk of Beuron; but like Boniface Wimmer before him he entered into private negotiations with the Vatican.  In 1883 he travelled to Rome and discussed with members of Propaganda Fide his hopes for a missionary society drawing inspiration from the Rule of St. Benedict.  Jacobini, secretary of the Congregation, was encouraging.  Amrhein then spent six months in Steyl, Holland, with Arnold Janssen, founder of the missionary Society of the Divine Word, through whose good offices Amrhein had first entered into communication with Propaganda Fide.  In August 1883 Amrhein was granted exclaustration by the pope: he was no longer subject to Abbot Maurus, nor was he bound any longer by a vow of stability to Beuron; rather his obedience was directly to Propaganda Fide. He thus became a Benedictine monk without a monastery.

The following years were difficult ones for Amrhein.  On the one hand he found support from various diocesan bishops for his project; but these preferred that the planned institute be non-monastic, and thus not exempt from episcopal jurisdiction.  Many of his Benedictine brethren remained suspicious of his venture, unsure how the active life of a missionary could be compatible with the life of a monk.  But in 1887 Amrhein’s goal was at least partially achieved when the community he had founded at St. Ottilien together with its missions in Africa were designated by Propaganda Fide as the “new German Benedictine Congregation for Foreign Missions.7

Subsequent years proved even more problematic as tragedies in the mission lands together with Amrhein’s own administrative incompetance jeapordized the future of the new Congregation.  It must have been particularly galling for Amrhein when in 1896 Archabbot Placidus Wolter and the Beuronese Congregation were asked to “put St. Ottilien in Order” by the bishop-visitator of St. Ottilien.  This was done, however; and in the same year members of the Congregation of St. Ottilien were granted the right of professing solemn vows, and the Congregation was accepted into the Benedictine Confederation.

Like Boniface Wimmer, Andreas Amrhein had been forced to circumvent the authority of his superior in order to implement his dream of missionary Benedictinism.  Both the American Cassinese and the St. Ottilien Congregations came into being as a result of Roman intervention in internal monastic affairs.