With his second wife , Adelaide of Paris , he had one daughter , Ermentrude ( 875 â `` 914 ) â '' who was the mother of Cunigunde , wife of the Count Palatine Wigerich of Bidgau ; they were the ancestors of the House of Luxemburg â '' , and a posthumous son , Charles the Simple , who also became a king of France . With his second wife , Adelaide of Paris , he had one daughter , Ermentrude ( 875 â `` 914 ) â '' who was the mother of Cunigunde , wife of the Count Palatine Wigerich of Bidgau ; they were the ancestors of the House of Luxemburg â '' , and a posthumous son , Charles the Simple , who would become , long after his elder brothers ' deaths , king of France .