Aaron Bunnell was born on January 30, 1828, in Pennsylvania. He married Clementine Lane, and they had at least seven children: Clara, born around 1850; Betsey, born around 1852; Mary, born around 1858; James, born around 1863; Minnie, born around 1865; Eleanor, born around 1868; and John, born around 1872. They lived in Auburn, Pennsylvania, and Bunnell worked as a farmer. By 1850, he owned $1,800 of real estate. A decade later, they owned $3,500 of real estate and $1,020 of personal property. An early biographer described him as a “large farmer and influential citizen of the township.”
In August 1862, he received a commission as a 2nd lieutenant in Company H of the 141st Pennsylvania Infantry. He fell ill soon afterward. As one of his comrades later noted, he was “unable to endure the fatigue and exposure of the field,” and he resigned on September 22, 1862. He settled in Washington, Pennsylvania, after leaving the army, and by 1870, he owned $8,000 of real estate and $1,600 of personal property.
He supported the Republican Party, and he ran for a position as county commissioner in 1871. He applied for a federal pension in May 1880 and eventually secured one. By 1890, he was suffering from chronic diarrhea, piles, and heart trouble. He died at Russell Hill, Pennsylvania, on January 7, 1894.