Adam Duncan was born in 1833 in Maine, Maine. He enlisted in the Navy during the Civil War. Boatswain’s Mate Duncan served on the U.S.S. Richmond during the Battle of Mobile Bay on August 5, 1864.

Adam Duncan’s Medal of Honor citation read: "The President of the United States, in the name of Congress, takes pleasure in presenting the Medal of Honor to Boatswain’s Mate Adam Duncan, U.S. Navy for extraordinary heroism in action, serving as Captain of a gun on board the U.S.S. Richmond during action against rebel forts and gunboats and with the ram Tennessee in Mobile Bay, 5 August 1864. Despite damage to his ship and the loss of several men on board as enemy fire raked her decks, Duncan fought his gun with skill and courage throughout the prolonged battle which resulted in the surrender of the rebel ram Tennessee and in the successful attacks carried out on Fort Morgan."

His hometown was listed as Boston, Massachusetts. His date of death and place of burial are unknown.

References:
Congressional Medal of Honor Society
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