Thomas Jackson Rodman was born on a humble farm near Salem, Indiana, on July 31, 1816, to James Thomas Rodman and Elizabeth Burton Rodman. He had six siblings. He entered West Point, in Orange County, New York, the iconic and prestigious military academy, in 1837. Graduating West Point in 1841, Rodman entered the service July 1, 1841. After being placed in the Ordnance Department of the U.S. Army, he served at Allegheny Arsenal until 1848, then moved to Richmond, Virginia, then to Boston, and to Pittsburg, Pennsylvania, in 1847. Thomas Rodman was developing a much more effective and reliable way to create the cannons that would be used in the Mexican-American War, as well as the Civil War. Thomas married Martha Ann Black in December 1943 in Pennsylvania.
In 1847, during the Mexican War, he served as ordnance officer at Camargo and Point Isabel Depots. In 1860, Thomas was living in Watertown, Middlesex, Massachusetts, with his wife, Martha, their six children, and two servants. He was listed on the census as being the commanding officer at the Watertown Arsenal. They had another son, Edmund, born in 1846, but he was not listed on the 1860 census. Rodman was assigned to the Watertown Arsenal in Massachusetts while he invented a way to create what would later be known as the strongest cast iron cannon ever made. This same cannon would continue to be used as coastal defense guns into the last half of the 19th century. The first 15-inch Rodman gun was completed in May of 1960.
The largest gun that Rodman developed was a 20-inch cannon that required a specially designed railcar to carry it. The Pittsburgh Gazette newspaper reported, “Juveniles, aged from ten to fifteen years, were amusing themselves today in crawling into the bore on their hands and knees. A good-sized family, including ma and pa, could find shelter in the gun and it would be a capital place to hide in case of a bombardment.”
Though the Rodman Gun is the most notable invention, Thomas also tinkered with gunpowder to help develop a more efficient powder which would allow a consistent and efficient burn and a faster speed of the cannon ball.
Rodman served in the military during the Mexican-American War and the Civil War, though his ability to design weapons placed him in less dangerous posts so he could help develop the nation’s arsenal. He was in command of the Watertown Arsenal during the Civil War. According to the Register of the U.S. Army in 1861, Thomas was a captain, in 1865, a major, and in 1867, Thomas was commissioned as a Lt. Colonel. At that time, Ulysses S. Grant was the commanding general of the Army.
In 1968, he was listed as the commanding officer of the Rock Island Arsenal as a Lt. Colonel and Brevet Brigadier General. He was brevetted Brigadier General, U.S. Regular Army, on March 13, 1865, for “faithful, meritorious and distinguished services in the Ordnance Department.” Most of the Union Army brevet ranks were awarded posthumously or on or as of March 13, 1865, as the war came to a close. The brevet rank does not usually come with an increase in pay.

Although a well-established inventor while serving in the Army, Thomas Rodman ran into trouble at the end of the Civil War while commanding the Watertown Arsenal in Massachusetts. This trouble would later be resolved by the numerous locals who came forward to support Rodman in his command of the arsenal. Although absolved of any wrongdoing, Rodman was soon sent to take command in Rock Island, Illinois, on August 4, 1865, to oversee the construction of the island.
In September of 1967, in addition to General Rodman, on post were a brevet major, brevet captain, two lieutenants, two sergeants, six corporals, and 55 privates or enlisted men. The enlisted men were busy cutting down trees, digging up roots, preparing fuel, clearing brush, cultivating parts of the island, growing corn and potatoes, and cutting hay.
General Rodman’s plan for the occupation of the island included a road around the entire shores of the island, shade trees, and graveled walks. A wide avenue would also be built up through the center. The only permanent building that was almost complete at that time was the arsenal building, which was 180 feet in length and 60 feet in width, and was four stories, including the basement. It was built of cream colored stone from LeClaire, Iowa, and had a 100-foot tower, which would soon hold a clock with a 3,500 pound bell. The commandant’s quarters, the barracks and the offices were all temporary wooden buildings at that time.
Many more buildings were to be constructed as part of his plan, with some underway in September. It was estimated that it would take 10 years or more to complete the buildings. But the plan contained so much more, including a laboratory, powder mill, commandant’s quarters, sewer system, officers quarters, park and lake, railroad, new bridge, a dam for water power, gas works, steamboat landing, and other projects.
At the time of his death on June 7, 1871, he was still in charge of completing the arsenal. He was buried among those he watched over. He died in quarters on post, of Angina Pectoris and Dropsy from heart disease. He had previously requested that his grave be “made within the shady precincts, and quiet loveliness of this spot, for which he had done so much to improve and adorn. His honored request is complied with, and most truly, yet with sadness, can we say “after life’s fitful fever he sleeps well.”
Due to his service and contributions during the Civil War, Rodman had a street in Washington D.C. named after him, as did many Civil War generals. It was an east-west street in the Northwest quadrant and is called Rodman Street, NW. The Army Register of 1872 lists Thomas under casualties as deceased June 7, 1871, at Rock Island Arsenal.
On August 31, 1971, an administrator’s sale was conducted for the personal property of General Rodman, consisting of 6 thoroughbred Southdown sheep, 41 improved sheep, and 50 head of cattle.
In March of 1872, his widow, Martha, filed an application for his Civil War pension. She died in 1908 in Berkeley, California, where she had moved with her sons and daughters after the death of Thomas. Their oldest son, John, was a retired Army colonel at time of her death, and both daughters were widows of Army officers.


THOMAS JACKSON RODMAN

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