roles sid el kar ( tenor ) hassi ( baritone ) mindar benjamin kidd ( comic baritone ) captain paul fontaine ( baritone or tenor ) azuri ( mezzo-soprano ) margot bonvalet ( soprano ) general birabeau ( baritone ) pierre birabeau/red shadow ( lyric baritone ) susan ( soprano or mezzo-soprano ) ali ben ali ( bass ) clementina hadji chorus of riffs , soldiers and inhabitants of the fortress synopsis french general birabeau has been sent to morocco to root out and destroy the riffs , a band of arab rebels , who threaten the safety of the french outpost in the moroccan desert .