Dabney William Diggs was born on February 10, 1837, in Shelby County, Kentucky. He eventually moved to New York City, and he earned a living as a clerk.
He enlisted in the Union army on May 27, 1861, and he mustered in as a private in Company C of the 83rd New York Infantry. According to his service records, he was 5 feet, 6 inches tall, with dark hair and grey eyes. He eventually earned a promotion to corporal. In the summer of 1862, he was promoted to 1st lieutenant in Company E of the 53rd New York Infantry.
Union officials transferred him to Company B of the 132nd New York Infantry and promoted him to captain soon afterward. Then, in January 1863, he was promoted to major in the 83rd New York Infantry. He mustered out in March 1863.
He returned to New York City after the war, and he earned a living as a dry goods merchant. He married a woman named Kate around 1862, and the couple had no children. By 1870, they owned $25,000 of real estate and $5,000 of personal property. By 1880, he was working as a real estate dealer in Big Stone City in the Dakota Territory. He returned to New York City in the late 1800s. He applied for a federal pension in 1887 and eventually received one. His wife died on July 6, 1923, and he passed away in New York City on October 19, 1924.