Define your start and end dates
I’m going through old Excel worksheets on siege data (it’s good to know you can open 20-year old Excel files).
Found this graphic, so I thought I’d throw it up here. In case you ever wanted a look behind the scenes of my dataset in the Appendices to my Vauban under Siege: Welcome.
This chart illustrates how spotty even secondary sources can be: sieges only have a limited number of possible start and end dates, yet historical narratives don’t find it worth their while to actually be consistent when they report these dates. Hence my need to develop a crazy-complex siege dataset: comparing multiple sources’ accounts of 100+ sieges, many of which had different stats, depending on whether you’re talking about the fortification under attack: fort(s), citadel, town.
Even after using a consistent method, the following graph should give you an idea of what’s available with English secondary sources on the Iberian theater (Kamen, Francis and Hugill mostly, along with a few articles):
You can see that there was much more consensus among historians concerning the end date of a siege, when the town capitulated, contrasted with when to measure the ‘start’ of a siege. You can also contrast it with a related visualization of sieges lengths throughout the campaign season in a previous post.
The number of days’ difference between the stages on both margins (BA to OT, Capit to BL) are usually not very great, so the margin of error is relatively small. But ideally you’d go to the primary sources (or maybe a detailed Spanish account) to make sure you’re comparing apples to apples. Overall I suppose I’m pretty content: at least my Spanish dataset was comparing oranges (Valencian) to oranges (Sanguinello, aka blood oranges). Of course I’m still expecting Björn Thegby and Andy Tumath to provide us all with a more complete dataset some time soon.
* For those not in the know: BA= Besiegers Arrive, IS= Investment Started, OT= Open trenches, OF= Open Fire, Chamade= self-explanatory, Capit= Capitulation, Garrison Evacuation, Besiegers Leave. Each start and end date pair means something slightly different, depending on what point you’re trying to make. Just make sure to be consistent and have a good reason why you chose the particular start-end pairing you did. And, please, avoid definitively exclaiming that there was only one ‘true’ start and end date. The study of siegecraft has suffered enough already from such formulaic thinking.