He entered the United States Military Academy as a cadet September 1, 1862, and was appointed second lieutenant, 4th Artillery after graduating in 1866.

He served as Chief Signal Officer in Cuba from 1898 to 1901, overseeing the construction of telegraph lines on the island.

The tests were considered a success, and secured future Army contracts for company founder Lee deForest.

By April 6 they had sent and received a message from Glengarriff Harbor, County Cork, Ireland, and Brooklyn, New York.

He found that increasing the contact pressure and adding an electrical bias to the detector improved its performance greatly.

Marconi used it in the first successful commercial station to signal across the Atlantic, between Louisbourg, Nova Scotia and Letterfrack, Ireland in 1912.

[7] It was replaced only gradually by the simpler galena and cat whisker detector of Greenleaf Whittier Pickard, and made a resurgence in the 1920s thanks to the efforts of Acheson's Carborundum Company.

His son, Halsey Dunwoody, was the Assistant Chief of the Air Service during the First World War and one of the founders of American Airlines.

The Brigadier General Henry Harrison Chase Dunwoody Monument and Park at Fort Eisenhower, Georgia commemorates his work in the Signal Corps and specifically his leadership in the reconstruction of the Cuban telegraph system after the Spanish–American War.