Arrière-ban, in French customs, is a general proclamation whereby the king summons to war all his vassals and their vassals. To the Provost of Paris belongs the convoking and commanding of the arrière-ban.
In the Medieval usage, arrière-ban denoted a general levy, where all able-bodied males were summoned into arms.
The arrière-ban was proclaimed throughout the Kingdom of France on April 30, 1337.
References
Arrière-ban Wikipedia(Text) CC BY-SA