On January 15, 1865, the North Carolina Confederate stronghold of Fort Fisher was taken by a combined Union storming party of sailors, marines, and soldiers under the command of Admiral David Dixon Porter and General Alfred Terry. Betham was a member of the naval storming party.
Medal of Honor citation
The President of the United States of America, in the name of Congress, takes pleasure in presenting the Medal of Honor to Coxswain Asa Betham, United States Navy, for extraordinary heroism in action while serving on board the U.S.S. Pontoosuc during the capture of Fort Fisher and Wilmington, North Carolina, 24 December 1864, to 22 January 1865. Carrying out his duties faithfully during this period, Coxswain Betham was recommended for gallantry and skill and for his cool courage while under the fire of the enemy throughout these various actions.
General Orders: War Department, General Orders No. 59 (June 22, 1865)