It was in Frankfort also where, not long afterwards, she found the great happiness of her life. The French Revolution, which had broken out in 1789, had grown constantly to greater and more dangerous proportions. In order to assist the threatened kingdom and its allies, who had taken refuge in multitudes along the Rhine, King Frederick William the Second of Prussia entered into an alliance with Austria. The French National Assembly quickly declared war, in April, 1792. Under command of the venerable Duke of Brunswick the campaign in France was so mismanaged that the Allies were obliged to retreat, and the French got possession of Mayence and on October 23, 1792, took Frankfort and burned it. The city was recovered December 2, but Mayence had to be besieged. The King of Prussia established his headquarters in Frankfort. On the outbreak of hostilities the Landgravine of Hesse-Darmstadt and her two granddaughters took refuge with their older sister, the Princess of Hildburghausen. From there the Landgrave, who was in the suite of the King, sent for them in order to present them to His Majesty, whose consort was also a native of Darmstadt. When the presentation had taken place, the grandmother intended to proceed with her charges that same evening to Darmstadt, but was detained by an invitation to the royal table. Here the twenty-three-year-old Crown-prince, Frederick William, saw the seventeen-year-old Louise. The charm and graciousness of her bearing, her delicate and youthful figure, and the sweetness of her voice affected him; and when she looked at him with an almost frightened expression in her large blue eyes, an inner voice seemed to say to him, as years afterwards he used to relate, “It must be she, or no one else on earth.” Louise had the same feeling; and a clear realization of their destiny (so the King declared in his reminiscences of that exalted moment) brought tears of joy to the eyes of both. The same evening, Prince Frederick Louis Karl, three years younger than his brother, fell in love with the fifteen-year-old Frederika. The brothers had been close comrades from childhood, and now, through their devotion to the two blooming sisters, they were drawn closer together than ever before.