“Batman”

batman

It must have meant:

batman
  • noun ( pl. batmen ) dated
  • (in the British armed forces) an officer’s personal servant.
  • ORIGIN mid 18th cent. (originally denoting an orderly in charge of the bat horse ‘packhorse’ that carried the officer’s baggage): from Old French bat (from medieval Latin bastum ‘packsaddle’) + man.

Yeah, that’s the ticket.