Born Sarah Bennett, on August 18, 1857, in Charleston, South Carolina, she made her first vows on the morning of February 3, 1882, while Mother Mary Lange lay dying.

On January 10, 1922, Sister Thaddeus was elected superior general of the community. At that time she was in Cuba. During her term of office (June 1923) the first graduation from four-year high at Saint Frances Academy took place. There were six girls in this class. Two later became Oblates. Mary Cecilia Bennett became Sister M. Theophane; Regina Beatrice Jackson became Sister M. Paschal. Their chief mentor was Sister M. Consuella Clifford, who would become superior general in 1926

After one term of three years, Mother Thaddeus was re-elected in June 1925. Sister M. Consuella Clifford was made vicar by that same chapter. At this time a change in the reception of orphans was being considered. It was proposed that orphans be withdrawn from Chase Street. They would be placed with the Franciscan Sisters (Mill Hill) who also cared for Black orphans. The change was a difficult and pain-filled one. From their beginning, the Oblates had always housed homeless children. In time, however, the change came to be considered a blessing.

Since the Sisters no longer had to support orphans, they were relieved of the need to beg. An additional benefit was the added space. Sisters on the missions were able to spend their summers at the Motherhouse. Community spirit among the Sisters was developed and strengthened. Mother Thaddeus had guided the community for just nine months of her second term when God called her to Himself. She had survived surgery for appendicitis, yet died a few days later, on April 8, 1926. At her funeral Mass the chapel was so crowded with Sisters and children and friends that many had to remain outside throughout the service.