Farnham spent several months during the winter of 1862-63 in Union camps near Fairfax Court House and Wolf Run Shoals, VA, with her husband, who had been appointed Lieutenant Colonel and placed in command of the 12th Vermont Volunteer Regiment. Farnham returned to Vermont in April 1863 and her husband was discharged later that year, after which he entered into a career in politics. When Roswell Farnham was elected governor of Vermont in 1880, Mary Farnham became the state’s first lady and played an active role in gubernatorial social events. 

Farnham was involved in a number of civic organizations in her town, including Bradford’s Relief Corps. She helped found the Ladies’ Public Library and was its librarian for many years. Her interest in literature led her to enroll in the Chautauqua Literary and Scientific Course, from which she graduated in 1884. She went on to earn one hundred and forty seals on her diploma and was recognized for this achievement at the 1906 Chautauqua Assembly in Chautauqua, NY.  Three of Farnham’s four children lived to adulthood: Charles Cyrus Farnham (1864–1937), Florence Mary Osgood (1866–1958), and William M. Farnham (1869–1927). Her first child, Roswell Phelps Farnham Jr., died in infancy in 1861. Mary Farnham died on June 13, 1913, having suffered a stroke two weeks prior.  

Topics in Farnham’s diary include living conditions in Union camps and towns near the front lines, the roles and expectations of women during the American Civil War, Washington D.C. in the 1860s, mid-century modes of travel, and health and medicine during the Civil War.