Should avoid the passive voice in an undergraduate history thesis?
PhatLobley, Well, writing as a GSI at your University, the passive voice should be avoided in the sense that most people here describe (active voice makes communication clearer). However, I would agree as well that mangling a sentence that has a natural passive voice is unnecessary and that an active voice does not solve all ills. Rather than worrying about active / passive, I would just think about verb choice in general (think about choosing a variety of good verbs, which can be hard if you are writing about relatively abstract subjects like culture or art). As a funny aside, I have had professors here at UM who insisted on the “i” voice as they found the use of “we” to be contrived… Different departments here vary quite a bit as to style and writing cultures…
As a practical matter, you should have a quick discussion about this with the professor or professors who will be grading your thesis. Find out what they think is important to observe, which at-least-nominal faults they don’t particularly care about, and what they want to see you do both in content and style. Then do what they say, and concentrate on what they say to concentrate on. It’s an undergraduate thesis, and the odds are that nobody but you, the graders, and maybe someone in your family will ever read it in that form, though it may well serve as the germ of a larger, less formal project. So I’d suggest simply trying to please your graders.