From William Shakespeare’s Henry VI, part 1 (II: 1):
Thus are poor servitors,
When others sleep upon their quiet beds,
Constrain’d to watch in darkness, rain and cold.
servitor: One that performs the duties of a servant to another; an attendant; in this case, soldiers.
[Middle English servitour, from Anglo-Norman, from Latin servÃ„Â«tor, from servÃ„Â«re, to serve.]