Alexander Doig joined the U.S. Navy 25 November 1861 as an acting first engineer and served for 36 months. he served on the USS Mercedita in the South Atlantic Blockading Squadron.
His report after the battle damage suffered by his ship in its fight with the Confederate ironclad ram CSS Palmetto State on January 31, 1863:
"USS Mercedita, Port Royal harbor, January 31, 1863
Sir: I respectfully beg leave to report the damage done to the boilers and machinery during the action this morning and the present condition of same.
"The enemy's shell penetrated the engine room bulkhead on the starboard side about 5 feet abaft the stern chimney, striking the port one and carrying away at least four feet of the outer shell.
"The steam immediately escaped from the boilers and filled the engine and fire rooms, thereby leaving the machinery in useless condition."
After an examination of it, he found that he could raise some steam and the ship could move under its own power which was when it was decided to take it to Port Royal for temporary repairs.
Doig resigned from the Navy on 6 June 1863.