John, Duke of Normandy, the son and heir of Philip VI, was placed in charge of all French forces in south west France, as he had been the previous autumn. In March 1346 a French army numbering between 15,000 and 20,000, enormously superior to any force the Anglo-Gascons could field, marched on Aiguillon and besieged it on 1 April. On 2 April the "arrière-ban", the formal call to arms for all able-bodied males, was announced for the south of France. French financial, logistical and manpower efforts were focused on this offensive.