Gunner

Gunner is a military position of a serviceman in the divisions (services, crews, groups, and sections) of various branches of the Ground Forces, who perform tasks related to the fire support of personnel from machine guns, weapon systems of combat vehicles, tanks, armored personnel carriers or soldiers from the maintenance of artillery systems, the primary duty the language of which in battle is aiming a gun (howitzer, mortar, etc.) at the target.[Bailey, J.B.A.]
The gunners and their guns are usually grouped in teams called either "crews" or "detachments." Several such crews and teams with other functions are combined into a unit of artillery, usually called a battery, although sometimes called a company. In gun detachments, each role is numbered, starting with "1" the Detachment Commander, and the highest number being the Coverer, the second-in-command. "Gunner" is also the lowest rank, and junior non-commissioned officers are "Bombardiers" in some artillery arms.[Hogg, Oliver Frederick Gillilan]

Sources:

Bailey, J.B.A. (2004). Field Artillery and Firepower. Annapolis: Naval Institute Press.

Hogg, Oliver Frederick Gillilan (1970). Artillery: Its Origin, Heyday, and Decline. London: Hurst.