Given the task definition and input, reply with output. In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.

Passage: 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.  Their dashing, daredevil leader is the mysterious "Red Shadow".  Margot Bonvalet, a lovely, sassy French girl, is soon to be married at the fort to Birabeau's right-hand man, Captain Fontaine.  Birabeau's son Pierre, in reality the Red Shadow, loves Margot, but pretends to be a milksop to preserve his secret identity.  Margot tells Pierre that she secretly yearns to be swept into the arms of some bold, dashing sheik, perhaps even the Red Shadow himself.  Pierre, as the Red Shadow, kidnaps Margot and declares his love for her.
To her surprise, Margot's mysterious abductor treats her with every Western consideration.  When the Red Shadow comes face to face with General Birabeau, the old man challenges the rebel leader to a duel.  Of course Pierre will not kill his own father, so he refuses to fight, losing the respect of the Riffs.  Azuri, the sinuous and secretive native dancing girl, might be persuaded to answer some of these riddles if only she can be persuaded by Captain Fontaine. 
Meanwhile, two other characters, Benny (a reporter) and Susan provide comic relief.  Eventually, the Red Shadow's identity is discovered, a deal is struck with the Riffs, and Pierre and Margot live happily ever after.
What is the real name of the person General Birabeau challenges to a duel?