Frank Eaton Stimpson was born around 1839 in Roxbury, Massachusetts, to Herbert and Mary Stimpson. His father was a stone dealer who owned $10,000 of real estate and $25,000 of personal property by 1860. Stimpson was baptized on November 24, 1839. He grew up and attended school in Cambridge, Massachusetts, and by 1855, he was working as a clerk.
He enlisted in the Union army on April 2, 1861, and he mustered in as a private in Company B of the 13th Massachusetts Infantry on July 16. On July 21, 1862, he became a sergeant in the 17th United States Infantry. He took part in the Battle of Antietam, the Battle of Fredericksburg, the Battle of Gettysburg, and the Overland Campaign. He was promoted to 2nd lieutenant on March 17, 1863, and he eventually earned a promotion to 1st lieutenant. He was wounded on May 12, 1864, in the Battle of Spotsylvania Court House, and he died on May 28, 1864.