
1) Military rank
Found on
https://www.crosswordclues.com/clue/matross

Matross was a soldier of artillery, who ranked next below a gunner. The duty of a matross was to assist the gunners in loading, firing and sponging the guns. They were provided with firelocks, and marched with the store-wagons, acting as guards. In the American army a matross ranked as a private of artillery. The word is probably derived from Fren...
Found on
http://en.wikipedia.org/wiki/Matross

• (n.) 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.
Found on
http://thinkexist.com/dictionary/meaning/matross/
Ma·tross' noun [ Dutch
matroos , from French
matelot .]
(Mil.) 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. [ Obsolete]
Found on
http://www.encyclo.co.uk/webster/M/33

A matross was an artillery soldier, immediately below the rank of gunner, who assisted in loading, firing and cleaning the artillery guns. Matrosses were armed with rifles and marched along with the store wagons acting both as a guard and to provide assistance in case a wagon should break down.
Found on
http://www.probertencyclopaedia.com/browse/FM.HTM
No exact match found.