Marshall Johnson Hadley was born around 1834 in Steuben County, New York, to Benjamin and Lydia Hadley. His father was a physician who owned $100 of real estate by 1850. He grew up and attended school in Jasper, New York. He married Harriet Merrick, and they apparently had no children. He worked as a farmer in Ceres, Pennsylvania, and by 1860, he owned $250 of real estate and $75 of personal property. His wife died in the early 1860s, and he married Mary Merrick on July 14, 1864. They had at least three children: Estella, born around 1868; Arthur, born around 1871; and Alda, born around 1879.
He enlisted in the Union army on October 12, 1861, and he mustered in as a private in Company F of the 58th Pennsylvania Infantry. According to his service records, he was 6 feet, 1 inch tall, with brown hair and brown eyes. The regiment spent most of the war in South Carolina and North Carolina, and he eventually earned a promotion to sergeant major. He was wounded twice during the war. In April 1865, he mourned President Abraham Lincoln’s death: “I am not ashamed to weep for the loss of one so good and true.” He added that the “blood of the soldiers friend mingles with the blood of the war worn vetrans and both cry aloud to heaven for its vengence on the heads of those who instituted the cursed rebellion.” He mustered out on January 24, 1866.
He settled in Annin, Pennsylvania, after the war, and he worked as a gunsmith. In July 1865, he received an appointment as a local postmaster. By 1870, he owned $500 of real estate and $400 of personal property. He applied for a federal pension in July 1890 and eventually received one. He supported the Republican Party, and he was elected county surveyor in 1889. He died in May 1902.