Anna was born on May 3, 1844 in Detroit, Michigan, and was the only child of a merchant father and pioneer woman. Her mother died when she was quite young, and soon thereafter, she moved with her father to Milwaukee, Wisconsin. Following her father's death, it became apparent that Anna was a natural nurse, who would care and cook for her friends. Upon turning sixteen, she married Mr. Etheridge, however the marriage failed and she returned to Detroit in 1861.
In April 1861, when the war began, she became one of twenty woman who enlisted with the 2nd Michigan Volunteer Regiment. When originally with this regiment, Anna only helped out with the laundry. When the 2nd Michigan left for Washington, D.C., to join the Army of the Potomac, Anna was the only one of the twenty who stayed on. She helped the wounded at Blackburn's Ford, as well as both battles at Bull Run. The soldiers gave her three nick-names; first was "Gentle Annie," then "Michigan Annie," and finally "that brave little sergeant in petticoats," following her appointment to sergeant by Union General Philip Kearney.
When the 2nd Michigan joined the Western Army, Anna transferred to the 3rd Michigan in order to remain with the Army of the Potomac. While serving as a nurse on the battlefields, she sustained a injury to her hand by a minie ball, as well as having her petticoats riddled with bullet holes. She was awarded the Kearney Medal for "noble sacrifice and heroic service to the Union army."
Anna Etheridge went on to serve in the Battles of Gettysburg, Bloody Angle, Cold Harbor, Belle Plaine, and Hatcher's Run. She also tended to the thousands of wounded soldiers who were transported to City Hospital following General Grant's siege on Petersburg, Virginia. At war's end, Anna married a war veteran and worked as a government clerk in Washington, D.C.
One of the Union soldiers she nursed, named George Hill wrote the following to Anna on his deathbed, saying, "Annie, dearest friend: I am not long for this world and I wish to thank you for your kindness ere I go. You were the only one who was ever kind to me since I entered the army."
Anna Etheridge's death date is unknown.