France might not have liked German unification, but I don't think they could have stopped it. What would they do? Invade Germany? That would be playing right into German hands since it was war that brought Germany together in 1871. Assuming Prussia could defeat Austria in 1866 and form the North German Confederation then I think it was too late for France to stop it. Could France do anything in 1866 to prevent German unification? They didn't historically, and I don't know that a larger French Army would make a difference. Napoleon III completely bungled that war by assuming it would be a long war and by offering to sell France's neutrality to both sides. France did not fully utilize her military potential in the 1860s. Napoleon wanted a larger army but could not overcome resistance to it, including from within the French Army who wanted a small but professional force.Would France have actually been willing to allow Germany to unify, though?