Eustachie de Tonnerre

✓ Eustachie of Tonnerre, Countess of Bar-sur-Seine, daughter of Milon V, Count of Tonnerre and Bar-sur-Seine, and Azeca; sister of Hugues-Rainard, Bishop of Langres, whose charter of 1072 names 'Walteri Breonensis comitis heredis mei et uxoris sue sororis mee'; wife of Gauthier I of Brienne. Source: Medieval Lands (fmg.ac, Cawley), 'Champagne - Brienne (chambrien)'; Medieval Lands (fmg.ac, Cawley), 'Burgundy Duchy - Tonnerre'. [DIRECT ANCESTOR OF THE COMPILER: flag added 22 Oct 2026 by walking the tree from Aynsley, so that this marker is reliable and can be searched.]