On Tuesday, the nonprofit Women on 20s announced the results of its poll asking who should replace Andrew Jackson on the $20 bill. The winner, by a margin of 7,000 votes, was former slave and Underground Railroad conductor Harriet Tubman.

It can be assumed that Tubman won the poll because she's a recognizable American hero. But putting her face on the $20 bill would be more appropriate than many of the poll's voters might realize.

Tubman's Civil War service earned her a pension — almost 35 years later

Tubman's work on the Underground Railroad often overshadows her service during the Civil War, when she served as a scout, cook, nurse, and spy for the Union. She only received about $200 during the Civil War, even though she was considered a valuable Union resource. After the war, Tubman and her husband, Nelson Davis, were chronically short of money.

each pension was a battle ...

Getting the government to pay pensions was a trial. Following her husband's death in 1888, Tubman's financial straits were more difficult, even after Congress passed a war widow pension law in 1890. Tubman was forced to provide thorough documentation and undergo a deposition to prove that she'd actually been married to her husband, who'd fought for the Union in the USC Eighth Infantry. Finally, in 1892, she earned the widow's pension of $8 a month.

By 1896, some Northern Republicans had started a campaign to give Tubman a full soldier's pension for her wartime service — $25 a month, the amount received by other surviving soldiers. Sereno E. Payne, a New York congressman, testified on Tubman's behalf. After sending supporting documents and Tubman's affidavit, the committee still doubted her claim of wartime service (the pension was about double what a nurse might receive). As recalled in Harriet Tubman: The Road to Freedom, the lengthy process resulted in the passage of a special bill to grant her a soldier's pension.

In 1899, the house passed bill HR 4982 authorizing Tubman a $25 pension for her wartime service. The Senate, however, bargained down the amount. So when President William McKinley passed the law in 1899, she didn't get the $25 a month that other Civil War soldiers received.

Instead, she got $20 a month.