He took commanded of the newly formed Armée de la Belgique – comprising 40,000 soldiers from the Valmy campaign – at Valenciennes on 20 October. Controlling enormously superior forces, ten days later he made his advance to Mons, late in the season and surprising the Austrians. On 6 November, he won the first great victory of the war at Jemappes near Mons and, this time advancing boldly, he overran the whole country from Namur to Antwerp within a month. He began planning the invasion of the Dutch Republic. Meanwhile, the French forces in the south had driven back the Piedmontese and had conquered Savoy and Nice in September, annexing them in November. Army of the Var commander Anselme invaded the county of Nice on 28 September, and forced the city of Nice to surrender the next day at 4 pm. On 7 November, the army was renamed Army of Italy. Another French success was the daring expedition from Alsace into Germany made by Custine, leading the newly created 14,300 strong Armée des Vosges from 19 September onward. He attacked Speyer on 29 September and conquered it the next day. He went on the occupy Worms and Philippsburg without a fight. Custine captured Mainz on 21 October 1792 and penetrated as far as Frankfurt, which surrendered on 31 October.