Lemuel P. Foss was born around 1842 in Strafford, New Hampshire, to Woodbury and Eliza Foss. His father was a farmer who owned $1,200 of personal property by 1860. He grew up and attended school in Strafford, and by 1860, he was working as a shoemaker.
He enlisted in the Union army on August 22, 1862, and he mustered in as a private in Company F of the 13th New Hampshire Infantry on September 19. The regiment took part in the Battle of Fredericksburg, the Bermuda Hundred campaign, and the siege of Petersburg. Writing from Fredericksburg in December 1862, he observed that the “rebs left every thing there was in the city we took a pianoforte and some nice cain bottom chairs to build our fire with. The houses are all stoven up and the boys are distroying every thing they can find.” He mustered out on June 28, 1865.
He returned to Strafford after the war, and he earned a living as a photographer. He applied for a federal pension in June 1866 and eventually secured one. He died of consumption on July 19, 1871.