First raised 1684 and originally named after the province of Nivernais, this was a single battalion regiment and at Minden formed a brigade on the right wing with the 2 battalion regiment Rouergue and single battalion regiment Tournaisis. The name was changed to Comte de la Marche in 1753 and to La Marche Prince in 1759. In 1776 the regiment became Regiment Conti and the ordonnance flag became entirely different. This one was carried from 1684 to 1776.
There is some debate about the distribution of colours on this flag; I have shown what I think is the most likely and pleasing of the possibilities. The 1753 "État général" volume simply says "2 Drapeaux, dont un colonel blanc & un d'ordonnance bleu, feuille-morte [dead leaf colour] and isabelle [coffee brown] par bandes dans les quarrés, & croix blanche", which does not help greatly, although taking it literally one might assume the quarters were coloured, from the top, blue, then dead leaf, then Isabelle!
UPDATE Th07.04.2022: The French 1721 Manuscript confirms this design for the flags; the regiment was then called Nivernois.
Unfortunately I have no 1757 illustration of these flags and the uniform. Basically the regiment probably had blue cuffs, all else being French off-white until 1761 when it acquired a blue waistcoat and collar; the pockets were horizontal with 4 copper buttons.
These flags complete the flags of the first line of the right wing infantry of the French army at Minden. Next will be Auvergne which formed a 4 battalion brigade in the second line of right wing infantry. The rest of the second line consisted of 3 French German regiments totalling 4 battalions. I haven't yet decided if I'll do the flags of French foreign infantry units at Minden as they're vastly more work; for now, I'll be doing just the French regiments so after Auvergne I'll be heading to the French left wing.
