Claim: John VI of Vendôme who married Jeanne de Ponthieu, a French noblewoman whose elder sister was Jean V de Harcourt, died in 1365.
Evidence: John VI de Vendôme (died 1365), Count of Vendôme and Castres (1354–1365) was a member of the House of Montoire and was the son of Bouchard VI (1290–1354) and Alix de Bretagne (1297–1377). In 1342, he married Jeanne de Ponthieu, they had two children: Jeanne de Ponthieu, dame d'Épernon, Countess of Vendôme and of Castres (Jeanne de Ponthieu, dame d'Épernon, comtesse de Vendôme et de Castres, before 1336 – 30 May 1376) was a French noblewoman, the youngest daughter of Jean II de Ponthieu, Count of Aumale. She had an elder sister Blanche de Ponthieu (before 1326 – 12 April/May 1387) who became suo jure Countess of Aumale on 16 January 1340 upon the death of their father. Blanche was the wife of Jean V de Harcourt, Count of Harcourt, by whom she had issue.