Anna Gruber was born at Bear Creek Township in Sauk County, Wisconsin, the daughter of Michael and Frances (Ruhland) Gruber. She was baptized by Rev. John Metzler at St. Luke Catholic Church in Plain, Sauk County, Wisconsin. Her sponsor was Justina Liegl.

Her first son, Albert Nachreiner, was born February 8, 1898, the illegitimate son of Simon Nachreiner (the husband of Anna's sister, Justina). It was on October 5, 1898 that Anna became the second wife of Joseph Blau at a ceremony held at St. Luke's Catholic Church in Plain. The officiant was Rev. John G. Laurer; witnesses were John Blau and Rosa Gruber.

Joseph's first wife, Anna Brückl, died in childbirth on April 25, 1898, leaving 5 children without a mother. The youngest son, Frank, was raised by his aunt, Mary Blau Brickl.

Anna Gruber and Joseph Blau had 4 children: Margaret Caroline (Ostermeyer), Anton Michael, George Joseph, and Clara Celia Blau. Georg and Clara did not marry and remained on the home farm south of Plain on Highway 23.

Obituary from the Weekly Home News, Feb. 20, 1958, page 5:
"In Memoriam - Mrs. Anna Blau - Mrs. Anna Blau, whose parents were Mr. and Mrs. Mike Gruber, was born October 30, 1877, and died February 8, 1958, at Sauk Prairie Memorial Hospital. Funeral services were held at St. Luke's Catholic Church Tuesday, February 11. A Solemn Requiem High Mass was conducted by Fr. Haines. Fr. Brechtl and Fr. Adams. She was a Gold Star Mother and a member of the Christian Mother's Society. She was preceded in death by a daughter, Anna, a son, Simon, and her husband, Joseph. Survivors include five sons; Joseph, Frank, Albert, Anthony and George; three daughters, Catherine, Margaret, and Clara; two brothers and five sisters, 43 grandchildren and 50 great grandchildren. Pallbearers were her grandsons, Edward Blau, Edwin Blau, Fred Ostermeyer, Francis Brey, Dan Blau and Dean Blau. Burial was in St. Luke's Cemetery.
Card Of Thanks - We wish to express our sincere thanks to Fr. Haines, Fr. Brechtl and Fr. Adams, the Christian Mother's Society, the men's choir, the American Legion and Auxiliary Unit 298, all our relatives, neighbors and friends for all the kindness shown us at the time of the death of our mother. For all the spiritual bouquets and floral tributes we are deeply grateful. The Family of Mrs. Anna Blau"