Webster's 1828 Dictionary
MATROSS
n.Matrosses are soldiers in a train of artillery, who are next to the gunners and assist them in loading, firing and sponging the guns. They carry fire-locks, and march with the store wagons as guards and assistants.
Webster's 1913 Dictionary
MATROSS
Ma *tross ", n. Etym: [D. matroos, fr. F. matelot. ] (Mil. )
Defn: Formerly, in the British service, a gunner or a gunner's mate; one of the soldiers in a train of artillery, who assisted the gunners in loading, firing, and sponging the guns. [Obs. ]
The Wordsmith Dictionary