Hundred Years' War English-occupied Calais. In a campaign reminiscent of Crécy, he found himself outmanoeuvred and low on supplies and had to fight a much larger French army at the Battle of Agincourt, north of the Somme. Despite the problems and having a smaller force, his victory was near-total; the French defeat was catastrophic, costing the lives of many of the Armagnac leaders. About 40% of the French nobility was killed. Henry was apparently concerned that the large number of prisoners taken were a security risk (there were more French prisoners than there were soldiers in the entire English army) and he ordered
Battle of Agincourt the battle was fought on a recently ploughed field, and there had recently been heavy rain leaving it very muddy, it proved very tiring to walk through in full plate armour. The French monk of St. Denis describes the French troops as "marching through the middle of the mud where they sank up to their knees. So they were already overcome with fatigue even before they advanced against the enemy". The deep, soft mud particularly favoured the English force because, once knocked to the ground, the heavily armoured French knights had a hard time getting back up to fight in