Decius Wadsworth was born in Farmington, Connecticut, on 2 January 1768 to a family that had lived in that colony for four generations. The childhood years of young Decius were spent amidst the uncertainties of the Revolutionary War. A second cousin, Jeremiah Wadsworth (1743-1804) had served during the Revolutionary War, first as Deputy Commissary General of Purchases for the Continental Army and then as Commissary General for both the American and French Armies. Decius entered Yale College when but 14 years of age. He earned a B.A. in 1785, and remained to earn an M.A. in 1788. Following several years as a struggling lawyer, Wadsworth responded in 1794 to publicity about Major General Anthony y Wayne's forth coming campaign against Indians on the frontier. He was commissioned a captain in the new Corps of Artillerists and Engineers in June, 1794. Several years of service proved less fulfilling than he had expected, and when Congress reduced the size of the Army in 1796, Wadsworth resigned. He returned to the Army in his former capacity in 1798, however, when it appeared that war with France inpended.
Wadsworth served with the 2nd Regiment of Artillerists and Engineers, and by 1800 had been promoted to the grade of major. W hen the Artillery a n d Engineers were divided, Wadsworth transferred to the engineers, and his first assignment took him to Fort Nelson, Virginia. H ere he repaired the defenses of the installation, but his work was soon interrupted. A dispute had arisen between Colonel Jonathan Williams, Chief of Engineers, and the War Department. Williams wanted engineer officers to command all elements, including line units, at installations where they happen to be the senior officer present, but the War Department refused to accept this position, and Williams then resigned.
As the next senior officer, Wadsworth became the Acting Chief of Engineers, and, following completion of assignments at Newport, Rhode Island, and New Orleans, he reported to the Military Academy. As acting Chief of Engineers. He automatically became acting superintendent.
Rather than attempt any major changes in the academic program, Wadsworth tried to tighten military discipline among the faculty and cadets, but his attempts to do so met with strong resistance. Throughly frustrated, he then tried to pick up the dispute which Colonel Williams had begun with the War Department, but President Jefferson took no action on the issue. Wadsworth therefore resigned his commission once more. The Secretary of War later compromised on the command question, which brought Colonel Williams back into the Army, but Wadsworth declined to take up his commission again, preferring more congenial employment in civilian life, and he then spent seven productive years as a merchant in Montreal, Canada.
When the War of 1812 broke out, Wadsworth was invited to take charge of the newly created Ordnance Corps in the expanding Army, and he accepted with enthusiasm. Appointed colonel and Commissary General of Ordnance, Wadsworth developed a small but highly efficient corps of younger officers, drawn largely from the Engineers. Wadsworth created arsenals in Albany and Pittsburgh in support of the Canadian campaign, made efforts to standardize weapons, particularly artillery, and in 1813, undertook to improve the coastal defense of the Chesapeake Bay region. During the fighting which took place around Washington in 1814, Wadsworth got into a dispute with Acting Secretary of War James Monroe concerning the placement of some artillery and offered to resign. His resignation was refused, but he was given a furlough. While he was on leave, Wadsworth's doctors strongly recommended that a cancerous finger be removed from one of his hands, but he refused to have the operation performed.
During his absence from Washington, the Army was reorganized, Congress created an Ordnance Corps, and Wadsworth became its first Chief. During the remainder of his tenure, Wadsworth stressed the principles of uniformity, simplicity and solidarity. Despite enormous obstacles, he and his staff managed to streamline the number and variety of small arms and heavy ordnance. Wadsworth's efforts to get the government to adopt an artillery carriage modeled on one adopted by the British failed when the new Secretary of War, John C. Calhoun, requested concurrence from a specially assembled Ordnance Board. Though the Board was specially chosen by Wadsworth, it ruled without a dissenting vote in favor of an obsolete French design, and Secretary Calhoun endorsed this decision. Some years later, after Wadsworth's death, the army recognized its error and reversed this decision. In 1821, Wadsworth fought a losing battle to prevent the Ordnance Corps from being amalgamated with the Artillery. He retired in June of that year and died of cancer at his home in Connecticut five months later on 8 November 1821, at the age of 53.