of which the French cavalry was used in WW1

The French cavalry saw use on the Western Front in 1914 and 1918 in the role of reconnaissance, flank/advance screening, mounted riflemen, and shock action, during the German offensives in those years. They saw some service on the Western Front in July, 1916, screening the advance of units from General Fayolle's Sixth Army on the Flaucourt Plateau during the opening of the Somme Offensive. Elsewhere, French cavalry was used in 1918 during the Army of the Orient's breakout from the Salonika Perimeter, which led Bulgaria to sue for peace.

Admittedly, English language writing on the French Cavalry seems sparse, but William Phillpott mentions the cavalry on the Flaucourt Plateau in his book Bloody Victory, about the Somme, and Gervase Philips highlights the French use of cavalry in WWI in his article Scapegoat Arm: Twentieth-Century Cavalry in Anglophone Historiography.

Hope that helps!