A lot of people at the time of the Civil War just thought that Mary was a slave. In the beginning she was "owned" by the Van Lew family. John Van Lew was a wealthy hardware merchant. When John died (1843) the women of the Van Lew family freed all of their slaves.
Mary continued to work for the family as a free, paid servant. After working a while for them, she was sent by Elizabeth Van Lew (the daughter) to an African American Quaker school. The conflicts between south and north started and she had to come back to Richmond, Virginia, before she finished her education. She began to work for the Van Lew family once again.
The war went on for a little while before Elizabeth asked Mary to help her and become a spy. Mary agreed to Elizabeth's proposal and started her life as a spy. She changed her name to Ellen Bond and started her job in the Confederate White House, for President Davis and his wife. Ellen (Mary) was considered "dim-witted, also slightly crazy, but able servant". Even though she was free, she still had to act like she was a slave.
Elizabeth trusted Mary with a big job, she couldn't do it by herself. Elizabeth needed the help because she was an important member of Richmond, but only because of her father's status and wealth. She was really apart of the Union, but she had to pretend to be on the side of the Confederates. Elizabeth helped the slaves and spies escape and she would also shelter them. Elizabeth was very helpful to the Union side of the Civil War.
Mary couldn't just "do her job" to get the information she needed. She had to listen in on the conversations about the troop strategies and movements. She did this while she was clearing the dishes and such. No one of the confederate side minded talking about this stuff in front of her because they thought she wouldn't know what they were talking about, or even remember. Mary did remember every single word said between the confederates, and she told a man named Thomas McNiven. McNiven was a baker. Their exchanges went unnoticed because he was "making deliveries" and she would talk to him briefly.
At the end of the Civil War the Mary was suspected for being the "leak" in the plans of the confederates. Mary fled when she was suspected, in January 1865. She tried to burn down the Confederate Capitol as one last act as a Union Sympathizer. Her attempt was unsuccessful. After that day, there was no record of Mary or her husband. They do not know when or where she died.
After the Civil War the federal government destroyed all records of the Southern Spies. Those files included Mary, Elizabeth, and Thomas and their actions during the war. This is one of the reasons that all of the dates and places aren't exactly in full detail. There are many stories to what happened to the diary Mary kept when she was a slave at the Confederate White House. Today the diary with all of the interesting information is still missing, there are many rumors to what has happened to the journal.
In 1995, the U.S. government honored Mary Elizabeth Bower for her efforts in spying, by inducting her in the "U.S Army Military Intelligence Corps Hall of Fame".
What was Said at the Ceremony
"Ms. Bowser certainly succeeded in a highly dangerous mission to the great benefit of the Union effort. She was one of the highest placed and most productive espionage agents of the Civil War. ... [Her information] greatly enhanced the Union's conduct of the war. ... Jefferson Davis never discovered the leak in his household staff, although he knew the Union somehow kept discovering Confederate plans."