A German attack from south-eastern Belgium towards Mézières and a possible offensive from Lorraine towards Verdun, Nancy and St. Dié was anticipated; the plan was a development of Plan XVI and made more provision for the possibility of a German offensive through Belgium. The First, Second and Third armies were to concentrate between Épinal and Verdun opposite Alsace and Lorraine, the Fifth Army was to assemble from Montmédy to Sedan and Mézières and the Fourth Army was to be held back west of Verdun, ready to move east to attack the southern flank of a German invasion through Belgium or south against the northern flank of an attack through Lorraine. No formal provision was made for joint operations with the British Expeditionary Force (BEF) but discreet arrangements had been made between the French and British general staffs; during the Second Moroccan Crisis in 1911, the French had been told that six British divisions could be expected to operate around Maubeuge.