What is "black troopers"

Trooper \Troop"er\, n.

1. A soldier in a body of cavalry; a cavalryman; also, the horse of a cavalryman.

2. A state police officer; -- also called state trooper.

3. A mounted policeman. [Australia]

   Note: The black troopers of Queensland are a regiment of aboriginal police, employed chiefly for dispersing wild aborigines who encroach on sheep runs.

4. Trouper.

   like a trooper, with energy, endurance, or enthusiasm; as, to work like a trooper.