like a trooper

Webster's Dictionary (GCIDE)

1.A soldier in a body of cavalry; a cavalryman; also, the horse of a cavalryman. [1913 Webster]

2.A state police officer; -- also called state trooper. [U. S.] [PJC]

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. [Webster 1913 Suppl.]

4.Trouper. [PJC]

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