Champagné was born into a family of French Huguenot exiles in Ireland,[1] the son of the Very Rev. Arthur de Robillard Champagné, Dean of Clonmacnoise, and Marianne Hamon, daughter of Colonel Isaac Hamon. His paternal great-grandfather was Chevalier Josias de Robillard, Seigneur de Champagné de Torxé, Saintonge,[4] who fled to Holland after the Edict of Fontainebleau in 1685,[5] joining William of Orange's army. He married Marie de la Rochefoucauld of the noble house of the same name. Their daughter Susanne married Henri de la Motte-Fouqué, baron de Saint-Seurin et de Tonnay-Boutonne, and was mother of Heinrich August de la Motte Fouqué. Their eldest son, Josias de Robillard (Forbes' grandfather), distinguished himself at a young age in service of Major-General Isaac de Monceau de la Melonière, who commanded a regiment of exiles in William's army during the Irish campaigns.[1] He married Lady Jane Forbes, daughter of Arthur Forbes, 2nd Earl of Granard.[6]
Promoted to lieutenant general on 25 July 1810,[13] he ceased officiating as Commander-in-Chief, India, following the appointment of Sir George Nugent, 1st Baronet in 1811.[14]