First raised in 1634, Rohan-Montbazon had 2 battalions. The regiment was at Rossbach (brigaded with Beauvoisis Infanterie), and was the third regiment in the centre column (the reserve) behind Provence and Poitou infantry regiments. It suffered heavily, losing 11 officers killed and 18 wounded. At Sandershausen in 1758 the regiment was battered by the Hessian attack, and, having used up all its ammunition, had to resort to the bayonet. Casualties were very heavy; 66 officers and 778 men were killed or wounded. At Lutterberg later that year the regiment was luckier and little engaged. In January 1759 it was involved in the relatively bloodless coup that seized the city of Frankfurt, which the French then held for the rest of the war. At Bergen in April 1759 along with Piemont and Royal Roussillon the regiment drove the allies back with the bayonet. In the last few years of the war the regiment garrisoned the Channel coast. [Details from Kronoskaf and C. Duffy's Prussia's Glory.]
The flags as depicted were carried by this regiment from 1745 to 1759.
And this plate shows the uniform and flags in 1757: