 Complete the following phrase:  It acquired the name in the 18th century, as it was the route taken by the two daughters of Louis XV, Adélaïde and Victoire, who were known as Ladies of France. At the time, it was scarcely a carriage road, but it was the most direct route between Paris and the Château de Boves, near Vauclair, on the far side of the Ailette. The château belonged to Françoise de Châlus, former mistress of Louis XV, Countess of Narbonne-Lara and former lady of honour to Adélaïde, whom the two ladies visited frequently. To make the way easier, the count had the road surfaced, and it gained its new name. The ridges strategic importance first became evident in 1814 when Napoleons young recruits beat an army of Prussians and Russians at the 