Finally, France declared war on Austria on 20 April 1792. Dumouriez planned to defeat the Austrian army within 15 days to achieve a successful quick victory. From Dunkirk to Strasbourg, the French northern frontier comprised 164,000 soldiers, divided into three armies under the leadership of general Lafayette (Armée du Centre; targets: from Givet to Namur and Liège), marshal Luckner (Armée du Rhin; targets: Flemish cities such as Menen and Kortrijk) and marshal Rochambeau (Armée du Nord; targets: Quiévrain, Mons and Brussels).