Who is Pierre Guerre from The Return of Martin Guerre and what is their importance?

Pierre Guerre is Martin Guerre's uncle. After the death of Sanxi (the elder), Martin's father, he becomes the head of the family. He also marries Bertrande's mother after she becomes a widow. Pierre accepts the "new" Martin for three years, but then Pierre becomes suspicious. He is annoyed by Martin's greed, and calls him an impostor. Pierre attempts a physical assault on Martin, and when that is stopped by Bertrande, Pierre has "Martin" sued for fraud and the impersonation of Martin Guerre. Pierre goes through much difficulty in carrying the suit forward, including being imprisoned himself during the trial in Toulouse.