Francis Price Longstreet was born on August 2, 1843, in Hawley, Pennsylvania, to Lewis and Elizabeth Longstreet. His father was a laborer who owned $600 of real estate by 1850. He grew up and attended school in Palmyra, Pennsylvania.
He expressed devotion to the Union during the Civil War. In May 1862, he denounced Confederates as "ungrateful sons who have risen up and are endeavoring to destroy the best government on which the sun ever shone." He enlisted in the Union army on August 20, 1862, and he mustered in as a private in Company A of the 137th Pennsylvania Infantry. The regiment took part in the Battle of Antietam, the Battle of Fredericksburg, and the Battle of Chancellorsville. He mustered out on June 2, 1863.
He settled in Erie, Pennsylvania, after leaving the army, and he earned a living as a bookkeeper. He married a woman named Mary, and he had at least two children: William, born around 1869; and Martha, born around 1870. By 1870, he owned $1,000 of personal property, and he employed one white domestic servant. He was admitted to the bar in August 1871.
He supported the Republican Party, and he played an active role in local veterans’ affairs. He joined the local Grand Army of the Republic post, and he spoke at Decoration Day ceremonies. In 1877, he celebrated the “brilliant exploits, and the grand achievements, of the Grand Army of the Republic.” He supported reconciliation, insisting that “Our armies met foemen worthy of their steel—their brethren and their countrymen.” He declared that “We are glad to mark the signs of a better feeling between the North and the South. Let us encourage the efforts that are being put forth to bring these two sections into closer harmony and sympathy.”
He moved to Lehighton, Pennsylvania, around 1876. An early biographer described him as a “fine lawyer with a good clientage [who] was universally respected in and out of the profession.” He died of tuberculosis on April 4, 1880.