Born: June 27, 1859, Louisville, Kentucky.
Died: June 5, 1916, Chicago, Illinois.
Buried: Cave Hill Cemetery, Louisville, Kentucky.
Pseudonym: Johann Tonsor.
Mildred was the daughter of William Wallace Hill.
A concert pianist, organist, author, teacher and musicologist, she is probably best remembered as co-writer, with her sister Patty Smith Hill, of the tune Happy Birthday to You.