Who is Bertrande de Rols, Bertrande Guerre from The Return of Martin Guerre and what is their importance?

Bertrande is the wife of Martin Guerre. She marries him at a young age, possibly as young as aged 10, when Bertrande just passes puberty. Her husband Martin is said to be impotent, and this is only relieved with the help of a magic "spell" of an old woman. Eight years after her marriage, Bertrande has a son, but shortly thereafter her husband disappears. When the false Martin appears after another eight years, she immediately accepts him as her husband and into her marriage bed.