Walker spent four months as a Confederate prisoner of war in Richmond, Virginia.
Despite her service tending to Union Army wounded and her imprisonment, Walker received a smaller pension than that given to war widows.
President Andrew Johnson presented her with the Medal of Honor in November 1865 to thank her for her contributions and her loyalty.
In 1917, due to changes in the medal's regulations, her award was rescinded because she did not engage in direct combat with the enemy.
Walker refused to return her medal and continued to wear it.
According to one legend, when federal marshals attempted to retrieve it in 1917, she opened the door holding a shotgun — and wearing her medal.
She died in 1919 — one year before women were finally allowed to vote.
Walker also attracted public scrutiny for her views on women's rights, which were seen as radical. She reportedly voted as early as 1871 — a half-century before women were legally allowed to do so in the US.
The illustration above, labeled a "Chamber of Female Horrors," mocks women's rights activists and is missing at least one notable item: Walker's Medal of Honor.
President Jimmy Carter reinstated her medal in 1977 to honor her sacrifice and acknowledge the sexism she fought.
In 2012, the town Oswego dedicated of a statue in her honor, drawing people from around the country remember her, according to The Post-Standard of Syracuse, New York.
"I have got to die before people will know who I am and what I have done. It is a shame that people who lead reforms in this world are not appreciated until after they are dead; then the world pays its tributes," Walker once said. That quote is inscribed on part of the statue.