John Merritt was born around 1840 in Harewood, England, to Thomas and Sarah Merritt. The family lived in Leeds, England, until around 1853, when they immigrated to America. They settled in Nelson, New York, and by 1860, Merritt was working as a farm laborer there.
He enlisted in the Union army on August 9, 1861, and he mustered in as a private in Company D of the 114th New York Infantry four days later. According to his service records, he was 5 feet, 4 inches tall, with brown hair and blue eyes. The regiment took part in the siege of Port Hudson and the Red River campaign. He was wounded on September 19, 1864, and spent the next several months recovering. He mustered out on June 8, 1865.
Merritt returned to Nelson after the war. He applied for a federal pension in February 1869 and eventually secured one. He married a woman named Harriet sometime before 1870. Their son Wilson was born in 1870, but he died later that year. Merritt worked as a farm laborer, and by 1870, he owned $300 of personal property. He also helped care for his father and his sister Sarah. They moved to Utica, New York, in the 1870s, and Merritt worked in a woolen mill. He remained in Utica for the rest of his life, and he died in 1912.