In the game, Kingdom Come Deliverance (set in early 15th century Bohemia), there’s a monastery that is quite well guarded. It has soldiers, walls and a watch tower. Is that scenario realistic for the period?

by TheLagDemon

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?

Mr_architect

I would say it is a very realistic scenario. There were several reasons why monastries had to be fortified and guarded:

  1. "Security" reasons - monastery was a place with quite valuable possessions - food, liturgical equipement, statues and decorations, etc. All this was pretty attractive for thiefs and robbers
  2. Local politics and strategy reasons - monastery was part of system of fiefs it was (in most cases) considerd to be on level of local nobelmans which could lead to the same situations as it would happen between two noblemans, f.e. arguing about borders or profitable sources of income which often lead to abushes or raids between two neigbours. The fact one of them was monastery did not change that much on the way how the situation was often solved (violently). Many local nobelmans vere often straight robbers which terrorized their neigbours and passing merchants or travelers. Monastery could also work as a political mean - the king (which considered himself to be "owner" of all monasteries) could use it to spread his influence or to reduce influence of his local opponent. Than it would again often lead to violent actions.
  3. Religious reasons - it would not happen that often but still it could happen. In fact (if we speak aboud KC:D) it happened 16 year later - the Hussites raised and one of their first targets were rich monasteries because they found it to be a very concentration of everything they hated (i.e. the corruption of Catholic church). It is quite ironic that against Hussites genial sieging abillities it was no help for monasteries to be fortified and guarded.
    I am talking mainly about monasteries in Bohemia but I am quite sure this was similar in most Europe at least in lands with similar culture. I have not deeply studied the bordering lands where could be a bit modified situation as it was often under cultural influence of "non-european" sources.
    I appologise for lack of sources I write this briefly from work with no time to search for exact books as I have this knowledge from a lot of different books I ve read during a long time.