Thomas Edwin Keen was born on January 4, 1839, in Lebanon County, Pennsylvania, to Lewis Keen and Susannah Armstrong. His father was a carpenter who owned $800 of real estate in 1850. He grew up and attended school in Pittsburgh, Pennsylvania, and in the late 1850s, he moved to Otoe County in the Nebraska Territory. By 1860, he was working as a farm laborer there and living with his friend James E. Brown.
When the Civil War erupted, Keen assured his family that he would not enlist. Soon afterward, however, he changed his mind. “As my crop amounted to little or nothing,” he explained to his sister, “I thought it my duty to go and serve my country.” He enlisted in the Union army on July 3, 1861, and mustered in as a private in Company H of the 1st Nebraska Infantry. According to his service records, he was 5 feet, 8 inches tall, with dark hair and black eyes. The regiment took part in the Battle of Fort Donelson, the Battle of Shiloh, and the siege of Corinth.
He remained fiercely loyal to the Union cause, reaffirming the “sense of duty I owed to my country.” He assured his family in April 1863 that he “did not enlist through impulse as many did…the light of that sense of duty and patriotism burns as bright today as when I first enlisted.” He denounced “Rebel sympathizers” and “Northern traitors,” and he celebrated the Emancipation Proclamation as “one of the best things that ever happened.”
Keen developed rheumatism around 1863, and by early November he was unfit for duty. He spent the next several months in a hospital in St. Louis, Missouri, before mustering out in July 1864. He returned to his mother’s household in Birmingham, Pennsylvania, after leaving the army, and he earned a living as a carpenter. He moved back to Pittsburgh sometime before 1890. He applied for a federal pension in July 1898 and eventually secured one at a rate of $8 per month. He was eventually admitted to the Soldiers’ and Sailors’ Home in Erie, Pennsylvania, suffering from rheumatism, heart disease, and “general debility.” He died of pneumonia on December 7, 1908, in Philadelphia, Pennsylvania.