Anna Katharine Rau was born at California, Missouri on December 12, 1864. Both parents were from Germany. She entered at Clyde on May 5, 1887 and was invested on September 10 of the same year. On November 17, 1888 she was professed as Sister M. Barbara. Being very frail, she was unable to assume the responsibility of a fully professed religious, and so became an Oblate. As such she served the Lord faithfully and devotedly in various capacities. With the other Oblates, she assisted regularly at Holy Mass, Benediction and Vespers in the side aisle of the chapel. In her earlier years she also participated in the Eucharistic adoration.

Sister was an extremely gentle, quiet, prayerful person, of "few and sensible words," always spoken in a soft voice. She was also very charitable and loved to do things for others. Neat and orderly at whatever task was assigned. She helped with the sewing and mending, and for many years had charge of the large refectory at Clyde. This was no small assignment, with close to one hundred Sisters, with individual napkin rings and silverware, placed according to rank and to the side on which they were in chapel. Often it became necessary for Sister to remove or put on napkins after Sister had all the tables arranged, and this caused much inconvenience at times. But Sister M. Barbara was kind and patient and never showed signs of irritation.

As her health declined, it was necessary for Sister to live in the infirmary. Nevertheless she continued to assist at Vespers and Benediction as long as she was able. Early in 1957 she had a serious sick spell, and though she recovered, she fell and injured her hip. This painful ordeal she also bore with patient resignation, and died a few days later at the Maryville Hospital, after undergoing surgery. Sister was ninety-two years old, and the date was February 8, 1957.