That's why I still swear on having a non-controllable default garrison on buildings, ships and siege engines against which one has to enter in "virtual combat" that would act as capture resistance and turn around limiter, and would made boarding and siege make more sense
I do use them often, as my first line of defense until I can afford better walls.
Also THANK YOU! I did not know you could connect Walls in this game and continue to work around corners!