army came upon a 19,000-man French corps by surprise in the Battle of Fère-Champenoise. Leading the advance, Frederick William decided not to wait for his infantry to catch up but to attack with his cavalry alone. The result was a crushing Allied victory as the French corps suffered losses of 2,000 killed and wounded while losing 4,000 prisoners, 45 cannons and 100 ammunition wagons. A nearby 4,300-strong French division with 16 cannons was also caught and completely wiped out. The Allies sustained 2,000 casualties out of 28,000 men and 80 guns engaged. At the Battle of Paris on 30 March, 6,500 Württembergers fought, losing 160 killed, wounded and captured. With the fall of Napoleon, Frederick William took the opportunity to begin divorce proceedings from his wife. He had been in the United Kingdom in June 1814 with his cousin Grand Duchess Catherine of Russia, the widow of Duke George of Oldenburg, and the two were in love. After Charlotte, King Frederick and King Maximilian Joseph had agreed to the divorce, a divorce court was convened by King Frederick on 31 August 1814. Both parties had indicated that the marriage was not consummated because of animosity. Annulment by Pope Pius VII, which was necessary because Charlotte was Catholic, did not take place until over a year later on 12 January 1816, shortly before the wedding of Frederick William and Catherine. Charlotte then married on 10 November 1816, the Austrian Emperor Franz I. Frederick William and Catherine also attended the Congress of Vienna from September 1814, where diplomats drew up a new Europe following Napoleon's downfall. After the return of Napoleon and the subsequent war in 1815, Frederick William commanded the Austrian III Corps which in one of the minor campaigns invaded France and besieged General Jean Rapp in Strasbourg. He was the only member of the ruling German royal families who participated actively as a military commander in the wars of 1814 and 1815. Wilhelm Hauff celebrated this in his poem Prinz Wilhelm. On 24 January 1816, Frederick William married Catherine in St. Petersburg. The newly-weds stayed in Russia for a few months and arrived in Stuttgart on 13 April 1816. Early reign Accession King Frederick died on 30 October 1816, at 1:30 am. On the same day, Catherine, who already had two sons from her first marriage, gave birth to their daughter Marie Friederike Charlotte. Although in King Frederick's declining