"[2] Hoadly was born in Hartford, Connecticut, on August 1, 1828, the eldest son of William Henry Hoadley and Harriet Louisa Hillyer.

Having earned his Bachelor of Arts degree, Hoadly then worked in the offices of the superintendent of public instruction while pursuing postgraduate education.

Later on, he also collected materials on Connecticut history, other state government documents, and the complete works of American statesmen.

After serving as its secretary for many years, he was elected president of the Connecticut Historical Society in 1894 and was annually reelected thereafter until his death.

At the time of his death, Hoadly was one of the longest-serving officials in Connecticut history, with one exception of George Wyllys, who had served for 61 years as Secretary of State (1735–1796).

Another brother, Frederick W. Hoadley, a major in the Union Army, had been killed in the Vicksburg campaign in June 1863.