What is the wealth equivalent in today's terms for how much would be needed to finance construction of a castle during the High or Late Middle Ages? Was it more tied to your title and lands, or could any one with sufficient wealth build and maintain a castle?

Since I have my sources up from the post on Marcher Lords, I’ll wade into this one! Again, disclaimer that I’m not as familiar with castle building/costs outside of Medieval Britain, and for this post I’ll be focusing specifically on Caernarfon and Beaumaris castles, two great Edwardian fortresses that were part of a system of castles Edward I commissioned during/after his conquest of Wales, and which were supposed to help pacify the perennially rebellious people of Gwynedd, or North Wales.

J E Morris, who painstakingly crawled through mountains of pipe rolls, pay tables, account booms and letters at the end of the 19th century, has some great statistics for us to look at.

Building a castle in Wales - still technically hostile country - was no small affair. Edward famously brought his experience from the crusades and more advanced castle building techniques to bear on his plan for fortifying Gwynedd against renewed Welsh unrest. Morris tells us that: “the town of Caernarfon was rebuilt and walled at a cost of £1024 and the castle was rebuilt and finished in 1299 for £4393.”

What’s more, these costs were not simply for a few builders and enough stone to keep them going. Morris goes on: “But besides workmen’s wages and the cost of material, there are also the garrisons of Caernarfon and Criccieth (another castle) to be paid, and Havering’s (the local royal representative) fee of £220 to be satisfied. Twenty men at arms, forty crossbows, and a hundred foot are guarding the works, while at Criccieth the Constable has ten crossbows and twenty foot.”

Caernarfon was of course the primary fortress of North Wales, but across a narrow straight of sea we find the island of Anglesey, famously the most important grain producing area for Gwynedd - much of North Wales is quite mountainous, and Welsh leaders like Llewelyn had relied on Anglesey to provide provender in the face of English aggression. Edward I, in fact, prioritised taking and holding the island during each campaign as a way to starve out his Welsh opponents. If Caernarfon was to guard North Wales, the new great castle at Beaumaris was to guard and secure the island of Anglesey.

Here we find evidence of a massive project that I Hope gives some idea of the scale. Morris reports that; “...the work, during the whole of the winter and up to the present, had been very costly, £250 being wanted every week. Four hundred masons are at work, some cutting and other laying the stones, 1000 less skilled artisans making mortar and lime etc, 200 carters, and thirty smiths and carpenters: 160 carts and wagons are in use, and thirty boats bringing up the stone. There is a garrison of ten men at arms, twenty crossbows and 100 foot.”

These were massive project involving thousands of workers of various skill levels. As Morris points out, “An Edwardian fortress was a serious piece of work, planned on a grand scale. The medieval mason was no jerry-builder, but a solid worker who required proportionally high pay. Edward was not the man to stint his servants, and he was keenly enough interested in the building.”

Morris tells us that “the works of Beaumaris were finished in 1298 at a total cost of £7041, besides the maintenance of Felton’s garrison of ten or twenty horse, twenty crossbows, and 100 archers.”

So ultimately these two castles alone cost upwards of £12,000 - and this doesn’t include works like Harlech, the Criccieth already mentioned, Flint, Conway, and more as Edwardian fortresses sprung up surrounding the traditional Gwynedd heartlands. Someone else could probably do a better job at providing context of how much this translates to in today’s equivalent, but suffice it to say that this was well out of the wheelhouse of any but the most powerful and richest of magnates. In fact, the continued battles with Welsh, Scots, French and the massive castle building campaign on top of it stretched Edward’s finances to the limit, which essentially played a huge role in the growth of Parliament’s power and responsibility in taxation and funding English campaigns etc.

Just another quick illustration - one of the largest non-royal castles constructed in this period is doubtless Gilbert de Clare’s Caerphilly castle in South Wales. The Clares were perhaps the preeminent family in English politics for almost a century, and their near-independent power over the massive marcher lordship in Glamorgan gave them unfettered access to resources that other English lords lacked. Otherwise castle building on this scale was quite often simply impossible for the ‘regular’ Baron.

Here’s Morris’ book that I quoted - I can’t recommend it highly enough if you’re at all interested in high Medieval English finances.

J E Morris, Welsh Wars of Edward I