John Davis Edgell was born on September 16, 1836, in Gardner, Massachusetts, to John and Elvira Edgell. His father was a farmer who owned $4,700 of real estate by 1850. Edgell grew up and attended school in Gardner.
He enlisted in the Union army on May 26, 1862, and he mustered in as a private in Company B of the 10th Massachusetts Infantry later that day. He mustered out on September 1, 1862, but he returned to the Union army later that month as a 2nd lieutenant in Company G of the 53rd Massachusetts Infantry. He mustered out on September 23, 1863.
He returned to Gardner after leaving the army, and he married Sarah Greenwood on December 24, 1863. They had at least two children: Harriet, born around 1865; and Calvin, born around 1870. They lived in Gardner, and Edgell worked as a bank cashier. By 1870, he owned $3,000 of personal property. By 1900, he was working as a bank president. His wife died on December 13, 1912. He remained in Gardner for the rest of his life, and he died on March 1, 1925.