Samuel Addison Lyon was born on July 15, 1844, in Pennsylvania to Henry and Mary Lyon. His father was a teacher. The family lived in Shaler, Pennsylvania, until the 1850s, when they moved to Duquesne, Pennsylvania.
He enlisted in the Union army on July 24, 1861, and he mustered in as a private in Company D of the 11th Pennsylvania Reserve Infantry. He denounced Confederates as “trater[s],” and he vowed to “do my duty” in battle. He urged his mother “not [to] be unesy about me for I will be cared for and I will care for my country…our hole harts is united we will up hold the Flag as long as we are spared and if I am slain in its defenc I wish no more than to be [wrapped] up in the stars & stripes.” He fiercely opposed emancipation. As he explained to his sister, "if I thought that I was fighting for to free the slaves I wold desert from the army. I belive that to extend slavery wold be very bad...yet I wold not fight for there freedom."
The regiment took part in the Seven Days’ Battles. Confederates captured him sometime in 1862, and he was briefly imprisoned on Belle Isle in Richmond, Virginia. He returned to the regiment by August 1862, and he died in the Second Battle of Manassas on August 30, 1862.