He is mentioned by Monaghan, who says that during the War Young Bayard "knocked two teeth" out of this "Australian captain" in a fight over a girl in a "London joint" (385). This officer's role closely resembles that of the unnamed Australian officer Bayard tells Rafe MacCallum about much earlier in the novel, but that officer was a major, and the nightclub was in Leicester.
This very peripheral character figures in one of Monaghan's anecdotes about his experiences with Bayard Sartoris in World War I as the "A.P.M." whose whistle Comyn took and used to start a melee in an Amiens night club called the Cloche-Clos (387). The Provost Marshals ran the army's military police.