First raised as a regular French unit in 1616, Poitou had 2 battalions until 1762. It was at Hastenbeck and then Rossbach, brigaded with Provence Infantry, where it suffered heavy casualties including its colonel. Before Rossbach the citizens of Gotha recorded French troops moving through the town and said the troops of Poitou were "finer and better equipped than all other French regiments" [that they'd seen from Soubise's army] (Wiltsche, 1858, Die schlacht von nicht bei Rossbach etc., pp.281-2). At Rossbach it led the centre column (the reserve) so received a hefty dose of Prussian musketry and cannon fire. In 1758 the regiment was sent back to France to garrison the coasts and then in 1761 returned to Germany where it was at the battle of Vellinghausen. In 1752 it was at Grebenstein and then the capture of the Castle of Amöneberg. At the end of the war it was stationed in Nîmes. [Details from Kronoskaf, Wiltsche from Google books and C. Duffy's Prussia's Glory.]
The flags as depicted were carried by this regiment from 1682 to 1791.
And this plate shows the uniform and flags in 1757: