David B. Churchill was born around 1838 in Vermont. He married Lydia Gray on July 15, 1858, and the couple apparently had no children. They lived in Providence, Rhode Island, and he earned a living as a jeweler. By 1860, he owned $300 of real estate.
He enlisted in the Union army on April 17, 1861, and he mustered in as a private in Company D of the 1st Rhode Island Infantry on May 2. He took part in the First Battle of Bull Run, and he mustered out on August 2, 1861.
He rejoined the Union army in February 1862, receiving a commission as a 2nd lieutenant in Company K of the 3rd Rhode Island Heavy Artillery. The regiment participated in the siege of Charleston. In August 1862, he declared that he was “readey and more than willing to do all in my power for the cause let the service be ever so hard and dangerous I hope and think I should do my dutey as well as I know how and be glad of the chance if it would help the cause.” He was promoted to 1st lieutenant in July 1862 and then to captain in May 1863. He mustered out on October 5, 1864.
He returned to Providence after the war and resumed his work as a jeweler. He apparently got divorced, and he married Emily McAlister sometime before 1880. By 1880, he was living in Brooklyn, New York. He died there on April 9, 1889.