Siege of Kenilworth Castle (1266)
Matrix Game for Students

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by Matt Fritz

The Simulation: The simulation is a matrix game, and for the most part follows the standard matrix game rules. Matrix games were invented by Chris Engle, and you can learn more about them on his website: Hamster Press - Engle Matrix Games. The complete rules for playing matrix games can be found on his website. The students should have a good knowledge of castles and the various methods for attacking them. Divide the students into six groups and assign them one of the commanders in the order of battle. It's a good idea to include a good student on each team. The simulation can be played in one period (one hour or less). The simulation could be continued for a longer period of time, or stretched out by playing just one turn per class period. Each team should be given a copy of the map and their commander's information. After the simulation the students should be asked to discuss their strategy. Compare and contrast their decisions to the real historical events.

Historical Background: In 1263 English nobles rose in revolt against King Henry III in what became known as the Barons' Wars. The dispute was over the noble's attempts to rein in Henry's extravagant spending. Under the Provisions of Oxford some of the King's power was transferred to a council of Barons. The King wanted to ignore the provisions, which led the Barons to revolt. At first the revolt was successful. Prince Edward was captured and imprisoned in Kenilworth Castle. However he escaped, and rallied the King's men. At the battle of Evesham in 1265 the rebels suffered a stinging defeat in which their leader, Simon de Montfort, was killed. Some of the rebels took refuge in Kenilworth Castle. From this strong base the rebels continued to cause trouble for the King. The King tried to negotiate a peaceful resolution but the rebels were defiant, and severed the hand of a royal envoy sent to negotiate with them. The King offered the rebels terms of surrender spelled out under the Dictum of Kenilworth. The terms set the costs for the rebels to buy back their lands, which had been seized, and required the men responsible for maiming the King's envoy to serve seven years in prison. The rebels refused the terms. The King prepared to take the castle by force.

The siege of Kenilworth Castle was the longest in English history. The attackers tried everything to take the castle using a variety of siege weapons, including trebuchets and siege towers. Their attacks focused on the north wall, which was judged to be the weakest part of the defenses. The defenders used the lake to bring in supplies, so the attackers built rafts and barges to stop them. They also tried to attack the castle by crossing the lake on barges. Finally, after nine months, disease and hunger forced the garrison to surrender. Under the terms of surrender the rebel barons were allowed to buy back their lands, which had been seized by the king. The siege cost a fortune, and ten counties were excused from paying their taxes for two years due to the cost they had incurred in support of the siege. The castle was given to Henry's younger son, Edmund, Earl of Lancaster.

Battle Report: This simulation was playtested with two students playing as King Henry and Prince Edward. The simulation lasted 45 minutes. The first two months of the siege proceeded quietly as Henry and Edward prepared for the attack. Portable bridges were built to span the moat in the north, where it was narrowest. Rafts were built in secret for an attack across the lake. Various siege weapons including ballista and trebuchets were constructed. Edward openly prepared to attack the defenses in the south, while Henry tried to conceal his preparations to attack from the north. By the start of the third month the attackers began to bombard the south wall, driving all non-essential personnel across the causeway to the safety of the island. In the fourth month Henry's siege towers were completed and he revealed his hand. His trebuchets began to bombard the north wall, concentrating fire on the towers. Edward led a daring attempt to attack across the lake during the fifth month of the siege. He waited for a rainy moonless night for the raid. The besiegers made diversionary attacks in the north and south to draw the attention of the garrison. Five hundred men carrying ladders boarded the rafts (which had been prepared in secret) and crossed the lake. They crossed in silence, with no lights to reveal their approach. The sound of a heavy rainfall prevented the garrison from hearing the approach of the rafts. The careful preparations were for naught. The attack was detected and had to be aborted. A second attempt was also thwarted by a garrison that was now alert to the danger.

During the sixth month the bombardment began to pay off. The two towers in the north had to be abandoned due to heavy damage. Henry ordered an assault on the north wall using his bridges and siege towers. He succeeded in gaining a foothold on the walls. A rash attempt to take the south walls by escalade was thrown back with heavy casualties. At last the south wall was
breached. As Henry's men swept the walls of the outer bailey Edward led his men into the breach of the south wall. The garrison was forced back into the inner bailey as Edward's men captured the causeway. The siege lost momentum in month eight as there were delays in moving the siege engines forward so they could fire on the inner bailey. Soon the delays were overcome and the inner bailey came under fire. After wearing down the defenses the attacker's took the inner bailey with a direct assault employing ladders. The surviving garrison was now trapped in the Norman Keep.

During month nine Henry and Edward quarreled over how to proceed. Edward wanted to offer the garrison reasonable terms of surrender, but Henry insisted that "all the traitors must die." Henry announced to his commanders that there would be no terms of surrender. Edward challenged his authority by openly opposing the decision, but he failed to sway his father. Henry was furious. He tried to order Edward off the field of battle in disgrace, but he had to back down in the face of a possible mutiny. The garrison was offered harsh surrender terms - the leaders would be exiled and the men responsible for maiming the royal envoy would be turned over for punishment. The garrison was out of supplies, so they reluctantly surrendered.

The Castle: The castle is protected by an artificial lake and surrounded on all sides by water. A curtain wall circles the island with towers on the three corners nearest to land. A gatehouse in the south leads to a walled causeway, which connects the castle to the mainland. A moat and curtain wall, with towers, protects the entrance to the causeway. The heart of the defenses is an inner bailey with another curtain wall and towers. The inner bailey is ringed by a dry ditch and anchored by the formidable Norman Keep, which sits on a hill and boasts walls nearly twenty feet thick. The only entrance to the Keep is on the second floor. More than 1,000 men under the leadership of Henry de Hastings garrison the castle. The defenders are well armed and supplied, and have siege engines of their own, including ballista and stone throwers.

Order of Battle


King Henry III
You are determined to deal harshly with the rebels. The Pope has given you his blessing and you rule by Divine Right. You must take the castle by force, or get the defenders to accept your terms of surrender. You want them to pay for the return of their lands, which you have seized, and turn over the leaders for punishment.

Prince Edward
You are the eldest son of Henry III so you will be the King when he dies. You sympathized with the rebels, and supported them for a time. But when push came to shove you remained loyal to your father the King. Although you were captured by the rebels and imprisoned in Kenilworth Castle earlier in the rebellion, you escaped. Then you led the army to victory at the Battle of Evesham.

Prince Edmund
You are the second son of King Henry III. Your brother Edward will inherit the throne, but this siege is a good chance to prove yourself. You have a reputation of being a chivalrous knight and you have taken a vow to join the crusades when this battle is over.


Henry de Hastings
You are in charge of the garrison of 1,200 men defending the castle. You realize that the rebellion is lost, but you can still salvage something if you can force the King to offer you reasonable terms of surrender. As the leader of the garrison you know that you will suffer the most if the castle falls.

Robert Ferrers, Earl of Derby
You have been a leader of the rebellion. The King has demanded that you pay seven years income for the return of your lands, more than he has demanded from any other rebel. You have little to lose from holding out. The siege will cost the King a fortune. Every day you hold out increases the pressure on him to offer more favorable terms of surrender.

Robert de Vere, Earl of Oxford
You were a follower of Simon de Montfort, the leader of the rebellion. Simon knighted you himself on the field of battle. Simon was killed at the battle of Evesham, but his son Simon the Younger has fled to France. You still hold out hope that he will return with an army to break the siege.

The Rules

Sequence of Play: During the turn each team gets to make one matrix argument. Start with King Henry, then Henry de Hastings, and continue alternating teams until everyone has had a chance to make their argument. The teacher should evaluate the strength of each argument when it is made and one student from the team will roll a die to see if the argument is successful.

Time Scale: The matrix arguments will vary a lot in how much time they take. Assume that each turn represents about six months of time.

Movement: There is no need to represent the detailed movements of either side. The defenders have a garrison of about 1,200 men, and can freely move within the walls of the castle. The attackers have a much larger force, about 5,000 men, and can freely move on the land around the castle. It will take a successful matrix argument to cross the water or walls.

Supply: The defenders have enough food and water for eight months. The attackers shouldn't be given this information unless they come up with a successful argument that would reveal this information (a spy or something). Successful arguments by either side could change this, and could also create supply problems for the attackers.

Matrix Arguments: During their turn each team gets to make one matrix argument . The team says something that happens, usually giving a reason why it happens. The argument can be about anything, it doesn't have to be about their character. The referee immediately judges the strength of the argument (how likely it is to happen) and the team rolls one 6-sided die to see if the argument succeeds. If the argument succeeds it becomes a part of the story of the siege, and can have an effect on the outcome.

Strength of Argument Die Roll Needed to Succeed
Very Strong 2, 3, 4, 5, 6
Strong 3, 4, 5, 6
Average 4, 5, 6
Weak 5, 6
Very Weak 6
Impossible Make up another argument

Some examples of arguments:
Supply – The defenders find out that some of their supplies have been spoiled and eaten by rats
Weather - Heavy rains turn the ground to mud and the water level around the castle rises
Fighting Spirit - The attackers lose heart because they've been camped outside the castle for six months and want to go home
Preparations - We build trebuchets and catapults to bombard the castle walls
Destroy or Repair Fortifications - After our bombardment a section of the north wall collapses
Assaults and Sallies - We use our ladders to attack the walls
Disease - The garrison is weakened by disease which spreads quickly because of the crowded and unsanitary conditions
Anything else the students can think up

Trouble Arguments: Sometimes a team will make a successful argument that causes trouble for the other side. For example, the defenders might argue that some of the attackers go home because the siege has gone on too long. In this case the teacher can allow the affected team to make a free argument to deal with the trouble. This will slow down the simulation, so the teacher decides when and if a team gets a free trouble argument.

Conflict Arguments: Sometimes a successful argument will lead to a conflict or battle. For example the attackers might argue that they attack through the breach in the north wall. In this case the teacher decides which side is stronger. The stronger side gets to make an argument describing the outcome of the conflict. If their argument fails the other side gets a chance to make an argument about the outcome. Keep alternating sides until one side makes a successful conflict argument.

Ending the Siege: The siege will end when the attackers can capture the Norman Keep, the defenders can successfully argue that the siege is lifted or abandoned, or one side successfully argues for a peace settlement. It's unlikely that the siege will end with a complete victory for either side. Once one side has gained an edge they should consider trying to end the game with a matrix argument describing terms of surrender that favor their side. If the students don't think to try this by the time the class is nearly over then the teacher should suggest the tactic. If time is running out decide which side is stronger and give the leader of that side a chance to say how the siege ends. If their argument fails give the leader of the opposition the same chance. If their argument also fails continue the procedure with the remaining teams until one of them is successful.

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