Thomas Jackson Rodman (July 31, 1816 – June 7, 1871) was an American artillerist, inventor, ordnance specialist, and career United States Army officer.

He is especially remembered for developing the Rodman gun, which in various sizes saw extensive use in coastal defenses, and was called the "strongest cast iron cannon ever made."

John Black Rodman was admitted on September 1, 1863, graduated on June 15, 1868, served initially with the 20th U.S. Infantry, and rose to the rank of colonel before retiring.

This process also "created internal strains and structural irregularities", and these problems were even more prevalent in large bore castings, especially on any actual openings in the cannon that were designed.

He found that if he cast the iron around a hollow core and then applied a steady stream of water within the barrel for cooling, a much more reliable and stronger product was made.

[3] Rodman experimented for almost a decade at the Fort Pitt Foundry in Pittsburgh, Pennsylvania, testing his theory and performing trial runs of his cannon barrels.

It tested successfully there in March 1861, but due to its size and weight it would be destined for permanent, fixed positions, and not suitable for field service nor naval use.

[6] Another innovation Rodman developed was a replacement for the rear knob of a cannon (called the cascabel) which is used for fitting the gear that lifted and lowered the gun.

Older designs had small round knobs, which were found to break easily on the larger barrels being cast at the Fort Pitt Foundry.

Using several of the arsenal's furnaces, about 160,000 pounds of molten iron were cast into four separate molds, then a week of cooling followed, and the cannon was finished on a huge lathe specially built for this task.

On July 23, 1864, 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.

His actions while in command of the Watertown Arsenal drew the attention of the powerful Congressional Committee on the Conduct of the War, who investigated allegations of Rodman's possible disloyalty, improper management of the facility, and misuse of government resources, among other items.

[10] In particular he was charged with the following: ... neglected to join officially in the observance of expression of joy at the surrender of the rebel General Lee, and of the sorrow at the death of President Lincoln.

[10]Almost 100 witnesses were called to testify before the Committee on this matter, however, Rodman was not permitted to cross-examine any of them; instead he was only allowed to refute these charges in a letter to his own commander, Brig.

To the charge he failed to properly celebrate the Union victory and mourn Lincoln, he stated: "that he had not fired a salute in recognition of the end of the war and of the President's death because he had never received official orders to do so."

Believing the Committee was hearing only "one-sided testimony" the civilians of Watertown wrote affidavits praising Rodman's performance, asking he remain commander of the arsenal, and demanding he receive a fair trial.