John H. Swarman was born on April 7, 1837, in Boston, Massachusetts, to Carson and Ann Swarman. He grew up and attended school in Medway, Massachusetts, and by 1860, he was working as a laborer there. He married Lucretia Hutchins on May 21, 1861. Their son Edgar was born in 1861, but he died the following year.
He enlisted in the Union army on May 25, 1861, and he mustered in as a private in Company E of the 2nd Massachusetts Infantry. According to his service records, he was 5 feet, 5¾ inches tall, with dark hair and dark eyes. He was court martialed in the fall of 1861 for an unspecified offense, and he forfeited three days’ pay. Confederate forces captured him near Winchester, Virginia, on May 24, 1862. He was exchanged on September 19, 1862, and he returned to his regiment on October 23, 1862. He was wounded in the left leg in the Battle of Gettysburg on July 2, 1863. He remained in the hospital for the next several months, and he mustered out on May 25, 1864.
Swarman returned to Medway after leaving the army, and he worked in a boat factory. His wife died in 1866. By 1870, he was living with his brother Frederick in Medway. He moved to Millis, Massachusetts, in the late 1800s. He applied for a federal pension in January 1885 and eventually secured one. He died in Rockville, Massachusetts, on September 9, 1914.