Allied military leaders have been meeting at the Chantilly headquarters of Joseph Joffre, supreme commander of the French. The war has not gone as well as expected this year and they hope that combined operations next year will break the deadlock.
Despite their failures this year the Allies still have many advantages over their enemies. As well as their economic might, the Allies have a clear advantage in manpower, with their numbers under arms dwarfing those of the Central Powers. To bring these advantages to bear, the Allies agree that next year there will be near simultaneous offensives on the Eastern, Western and Italian fronts, to prevent the Germans and Austro-Hungarians from concentrating their reserves on any one danger point. The British and French tentatively agree a huge joint offensive on the Western Front, most likely at the junction of their two armies.
Confident that 1916 will see a turnaround of their fortunes, Allied commanders leave Chantilly and return to their own headquarters. It does not occur to any of them that their enemies might have plans of their own.
Joffre & French at an earlier conference (Today in World War I)