The real last name of Charlotte is unknown, although according to a few sources her true name was Elsa Jane Guerin. The name she used to enlist in the Union Army was Charley Hatfield. She was born in a rural Iowa town in 1840. In 1858, her mother died when Charlotte was 18 years old. Her step-father treated Charlotte as a hired hand. When she was only 19 years old, she eloped, but her husband spent most of his time away from Charlotte, due to gambling habits. After giving birth to a stillborn baby, Charlotte's husband beat her severely and left her. She later heard that her husband left her to be with another woman. She subsequently vowed revenge on both her husband and his mistress.
To get her revenge, Charlotte decided to travel West with her mule to find her husband. During her trip, she successfully disguised herself as a man in order to avoid the problems of a woman traveling alone. Along the way, she met an old friend named George West who was partaking in the hunt for gold at Pikes Peak. In each town she visited, she was able to gather information to track down her husband and his mistress. Finally, after arriving in Colorado, she faced the two of them and exacted her revenge, though the details of their encounter are unclear.
Charlotte shared her story with George West, asking him to swear that he would not share it for 25 years.
At the start of the Civil War, both George West and Charlotte enlisted, George served as an officer in Colorado while Charlotte became a member of the 3rd Iowa Cavalry Regiment at Keokuk, Iowa. Being that women were not able to serve, Charlotte enlisted under the title of Private Charley Hatfield, dressing up now as a man. "Charley" worked as a spy for General Samuel R. Curtis where she "volunteered to infiltrate the Confederate lines dressed as a woman carrying eggs from her home." The Confederate Army would take her into their camp and allow her to sell her eggs to the soldiers, picking up valuable information from the men while eavesdropping. This gained the Union their victory in the Battle of Westport. During the battle however, she was injured after her horse was shot while riding. Charley sustained a gunshot wound in the leg and a cut on the shoulder. She was brought to a Confederate hospital to be treated when the doctor, Jesse Terry, realized that Private Hatfield was actually a woman. Charley was able to convince Doctor Terry to keep it a secret, and Charley was transported to a different army hospital in Ft. Leavenworth, Kansas to completely recover.
Charley later found out that General Curtis had written to the Governor of Iowa to have Private Hatfield promoted to 1st Lieutenant. The approval came from the Governor and Charley was promoted as well as made aide-de-camp to General Curtis. Charley served for the remainder of the Civil War, never having anyone discover that she was in fact a woman.
After keeping his promise for 25 years, George West finally told Charlotte's story on January 14, 1885 by published an article in a paper. Charlotte read it and wrote to George, saying she had been remarried and living happily with her husband and four children for eight years at that point. Charlotte asked West to keep her name and address a secret, thus being why we do not know her true last name.
There have been several versions of the "Mountain Charley" story. In 1861, her story first appeared in an autobiography exploring her journey dressed as a man in California and Colorado. Two drastically different versions of Mountain Charley were written in Western newspapers later on. "In one adventure series, Mountain Charley joins a Wisconsin regiment, fights through the war, then goes to Wyoming, where she runs a gambling house, and by 1879 lands in prison." The second story reads much like the one General George West published.
Based on research, the history of the 3rd Iowa Cavalry perfectly matches the story General George West's account of "Charley." However, no Charles Hatfield was found on the roster of the 3rd Iowa Cavalry. A Charles Hatfield enlisted in Company F of the 23rd Iowa Infantry, but was supposedly rejected on September 19, 1862. It may be possible that Charlotte Hatfield, also known as Elsa Guerin, failed on her first attempt to enlist, but was successful on a second attempt. No personal record could be found to support this theory
Because there are many different versions of the story, it may be likely that Charlotte Hatfield's story "was a composite of the experiences of several woman settlers."