The song that instantly jumped into my head was Bathory's 'One Rode to Asa Bay'.
The lyrics describe a peaceful northern middle ages village called Asa. A company of Catholics arrives and orders the villagers to slave for them to build a "house for god" (Church). The village elder rejects and stands up for his people, tells god to build his own house and tells them tales of their own gods and lords, only to be slain there and then. Most of the song after this describes the villagers, from eldest peasant to women and children, slaving under whip and chain to build a hall that could "fit two dragon ships inside".
Finally, once they had finished and thought they were free once more, the musician (Quorthon - R.I.P) sings a famous (at least famous for the genre) line - "People of Asa land, it has only just begun", signalling further tyranny ahead for them. The rest of the song is instrumental.
Not only is the song an amazing story, and well written, I think it is quite depressing as well seeing how this shit actually did occur back in this times en masse. Here's the song at any rate:
