Marie Thérèse was the sole surviving child of Louis XVI and Marie Antoinette. She was born in 1778. Her life was repeatedly rocked by political upsets in France as her country worked out what form of government was suitable. She married her cousin Antoine, the Duc d'Angoulême, in 1799. She died in 1851 as a French Republic was about to turn into the Second Empire. Her Wikipedia article is here.