[2] The French garrison began demolishing buildings outside of the walls to avoid giving cover to the attackers, however two large monasteries were still being prepared for demolition when the English vanguard, led by Thomas of Lancaster, Duke of Clarence, arrived.

[2] Having installed a prefabricated bridge over the river,[2] Henry began the siege on 18 August[4] with an artillery barrage on the lower town.

[1] Henry also attempted to undermine the walls, but the defenders set up bowls of water on the ramparts so that by observing the ripples, they could detect the English digging and countermine, fighting the attackers underground.

[2] The commander of the French garrison, Guillaume de Montenay, having refused to surrender, Henry planned an assault on 4 September.

[8] English chroniclers are at pains to praise Henry, who ordered that no women or priest should be harmed or churches plundered;[9] however, his men forced anyone they could find into the market place, where they massacred between 1,800[10] and 2,000 people.

[11] While the siege was still in progress, Clarence had written to the Lord Mayor of London saying that English settlers would be required to populate the town and when they later arrived, they were allocated vacant houses to live in.

The desperate Siege of Rouen lasted from July until January 1419, but its capture secured the whole of Normandy as a base from which he could press on towards Paris.

[13] Caen remained in English hands until 1450 when it was besieged and taken back during the French reconquest of Normandy in the closing stages of the war.