[2] Dyer's military career began in October 1856 when he enlisted in the First Light Infantry, a prestigious unit of the Rhode Island Militia located in Providence.

On the outbreak of the Civil War, Dyer enlisted as the 4th sergeant of the 1st Light Artillery Battery of Rhode Island on April 15, 1861.

Dyer was discharged shortly after his arrival due to accidental injuries he suffered after an explosion of a limber chest, on April 21, 1861.

On June 7, 1869 he was elected lieutenant colonel commanding the Providence Marine Corps of Artillery, serving until April 24, 1871.

Upon his father's death, in 1890, he succeeded to First Class membership in the Military Order of the Loyal Legion of the United States.

Dyer was admitted as an hereditary member of the Rhode Island Society of the Cincinnati in 1898 by right of his descent from Captain William Jones, a veteran of the Revolutionary War.

He joined the Rhode Island Society of the Sons of the American Revolution in 1899 and served as its president from 1903 to 1904.