Also, were there monasteries (or similar religious institutions) that had defensive structures or troops stationed on site? Did that change at all over the course of the Middle Ages, or were there any differences across regions?
And on a related note, did Christian Kingdoms ever sack each other’s churches or monasteries during war (outside of the fourth crusade)? Perhaps during post-reformation Catholic/Protestant conflicts?
I would say it is a very realistic scenario. There were several reasons why monastries had to be fortified and guarded: