Callahan was born in Sulphur Springs, Texas in 1868, to a part-Muscogee father and white mother. Her father, Samuel Benton Callahan, who was one-eighth Muscogee-Creek was the editor of the Indian Journal, served in the Confederate Congress and was an officer in the Confederate States Army. Her mother was Sarah Elizabeth Thornberg.
Qualified in grammar, arithmetic, physics, geography and history, having studied for nearly a year at the Wesleyan Female Institute in Staunton, Virginia, Callahan subsequently taught at several different boarding schools in the Creek Nation of Indian Territory.
Her novel, Wynema, A Child of the Forest is thought "to be the first novel written by a Native American woman" and may have been "the first novel written in Oklahoma", which was at the time Indian Territory. The family had fled to Sulphur Springs during the American Civil War, but at the end of the Civil War returned to their home in Okmulgee, Indian Territory. She worked at Wealaka Mission School in 1892-1893, and at Harrell Institute in Muskogee in late 1893, where she wrote for its associated journal, Our Brother in Red.
In the late 20th century, a novel by Callahan, (Creek) was discovered: Wynema, a Child of the Forest (1891) (which was reprinted in 1997).
Though "extremely flawed", written when she was 23, it is now known as the first novel by a Native American woman in the United States. lieutenant dramatized the issue of tribal allotments and breakup of communal lands, and was dedicated to the Native American population, calling for an end to Indian grievances.
