Francis Long was born on December 8, 1819, in Claremont, New Hampshire, to Simeon Long and Chloe Steele. His father earned a living as a sea captain. He attended Kimball Union Academy in Plainfield, New Hampshire, in the mid-1830s. By 1860, he was living in his brother Hiram’s household in Claremont. He married Lucia Jane Phillips on October 13, 1862, and they had at least five children: Henry, born around 1867; Bessie, born around 1869; Susan, born around 1872; Bernice, born around 1875; and Walter, born around 1879.
He enlisted in the Union army on September 1, 1862, and he mustered in as a corporal in Company E of the 16th Vermont Infantry on October 23. The regiment took part in the Battle of Gettysburg. Writing from Gettysburg on July 2, 1863, he assured his wife that “I have done faithfully my duty so far and I shall not back out now.” He added that “if any thing should happen to me you will have the satisfaction of knowing that my heart is with you to the last and that in all things I am well pleased and satisfied with you.” He survived the battle, and he mustered out on August 10, 1863.
He settled in Concord, New Hampshire, after the war, and he earned a living as a farmer. By 1870, he owned $300 of personal property. He moved to Milford, New Hampshire, in the 1870s, and then to Nashua, New Hampshire, around 1886. He applied for a federal pension in September 1890 and eventually received one. He died of a cerebral hemorrhage in Nashua on January 14, 1909.