Source 3 is moderately useful as it is a timeline for Dover Castle and it shows at what dates that the castle was updated and in some cases what it was used for, but it does not show what the improvements were. It shows that in the early stages it was used as a traditional castle with the defenders inside and the attackers outside trying to get in, but it seems that later on after the time period in the question, the castle changed roles to prison and then eventually as an headquarters. On the other hand the only labels that are within the time period are the improvements that were made to the castle and the siege that took place in 1216.
Source 4, on the other hand, does show the changes that were made to the castle and at what times. There are four pictures with the first one in the Iron Age and the last one at the end of the 13th century. The first one just shows the evidence of a Roman and Saxon settlement and so is not very useful except to show that the castle was built on an established area for earlier civilisations. Otherwise, the rest of them show the development and major changes through to the 13th century. If you link this source to other sources like Source 3 where the timeline says when the changes were made, sources 6 & 7 where you can build up a detailed picture of the siege and can place where things happened.
Source 5 was written in modern day England after all the modifications were made to the castle and the castle was made open to the public. As a result, it has a lot of information on the history of the castle and the people who were involved with the castle in some way. However, as it is written in modern day it is based on probability and it is biased towards the good side of the castle as it came out of the guidebook. Again used in conjunction with other sources this would make a valuable resource and paint a picture as to what was happening to the castle.
Sources 6 & 7 are narratives as to what happened in the siege of 1216 from an English point of view and from a French point of view. As the English were the victors in this, the statement seems to skip out the details and concentrate on the individuals and their actions. The French point of view, as they were the losers in this fight, is more sober and contains more detail of what happened during the fight. It notes what kind of defences the English used and what the terrain was like. He writes about the mining that was used to try and undermine one of the towers of Dover castle. The bad side of the source is that it stops at the death of King John leaving us to rely on the English point of view which is quite dangerous without supporting sources also dealing with the same time period. This was a time when Dover had just been reinforced as a building and the keep had just been finished. The castle was originally built to keep the English calm and to protect William’s troops. After this time when attacks from France was more likely, the castle was upgraded to reflect this new job and it worked as the French did not manage to break through and eventually gave up after great damage to the garrison and castle.
Sources 8 & 10 are from French illustrations drawn around 1250. It has the armour and weapons of the period. Although these are drawings from just after the siege, they are drawings and all depend on the artist’s view of the battle or indeed if he was even there. Source 10 is almost exactly the same as Source 8 just without the horse behind the knight. The similarity shows that the original drawing was copied and so if this was changed, then so could Source 8. So these by themselves have almost no bearing on how the castle has changed other than it had to be rebuilt and the castles did have square towers at that time.
Source 9 is from a manuscript 100 years later and you can clearly see the trebuchet and ladders which shows the changing nature of warfare to heavy projectiles. You can also see that the towers have become rounded to spread the force of the impact to stop the towers from falling easily to heavy stone/iron balls. You can see two of the men holding and firing a crossbow that shows the advancement of other smaller projectile weapons. If used with previous Sources, you can see the change of the nature of castles from specifically holding knights and primitive arrows to holding out trebuchet balls and other siege implements.
Source 11 & 13 are both from the 18th Century and although are past the time period, they are in ruins which shows that they have been left alone for a while and you can clearly see the covered link in Source 13 and the curtain wall in Source 11. Again the changed form of the castle can be seen. But as these are illustrations again they cannot be totally accurate and this was a time when the keep was used as a prison so it would be unlikely that the artists would have frequent opportunity to draw the castle.
Source 12 is from the 16th Century and also shows the covered walkway. It is a picture of the whole castle and if you compare it to earlier manuscripts and drawings, differences can be seen as improvements were made through the centuries.
Source 14 is a modern photograph of Constables Keep and the caption says that it is much the same as in the 1220’s apart from the modernised above gate-passage level. Things will have been reconstructed as the timber and stonework would have fallen into disrepair but the shape and construction of the castle remain the same.
Dover Castle has not really been a ‘typical’ castle as it is sited on the coast and is a prime place for enemies to invade. So therefore, the fortifications have been stronger and the castle much more able to withstand a long siege as 1216 showed. The different sources all show different things to varying degrees of usefulness for this question. The most reliable sources could be said to be from the time, as they have no use for large-scale propaganda to sway the public’s opinion in favour. In those days the monarch or lord ruled and what commoners thought did not really matter as long as they worked. The manuscripts were useful as they are from the time and they are where historians would get a lot of their knowledge. Castles in England and Dover Castle in particular have changed roles through the period. At first they were to pacify the country but as this happened, they were slowly modified to face outwards and to protect the country from other enemies such as France.