The PhD viva (oral defence of the thesis) is the final rite of passage for PhD students in Britain and elsewhere (although I get the impression that it doesn’t happen in the US at the very end, but there are other stages of the PhD process – the defence of the thesis proposal – that involve something very similar?). But there has in the past been very little to help them prepare for it, making it an even more nerve-wracking prospect. It’s long been a rather mysterious ritual, held as it is (in Britain) behind closed doors. (Our department has very recently introduced mock vivas to help counter this; I suspect it’s part of a wider trend in which increasing emphasis is being placed on good preparation and support to help students survive.)
It should not be that scary. It should be a positive and rewarding experience, an opportunity to rabbit about your pet obsession of the last three years to a captive audience. And it should not be a confrontation, but an exploration of the stuff in your head that underlies the words on the page (apart from anything else it is, of course, testing that you did the hard work of research and wrote those words yourself). There may well be some questions, say, about why you did X rather than Y (part of your viva preparation should be thinking about the weak spots and how you might respond to questions about them), but unless there’s something very wrong with your thesis, you should not be and should not feel under attack. It’s much more about establishing that you’ve understood your material and its significance to a wider field of study. A PhD thesis is a kind of apprentice piece. It’s meant to show that you’ve learned the essential skills of the discipline; and at the same time, have contributed something worthwhile and new (in some small way) to that discipline.
Nearly everyone who gets this far ‘passes’. It is not a rubber-stamping exercise, however; far from it. Nearly everyone will also have to make corrections of some kind; in some cases, more substantial than others. Things can go horribly wrong (more likely than failure is to have to rewrite substantially and resubmit, or, possibly worse, be awarded only an MPhil with no option to resubmit), but this is unusual. It can also go a little awry if the choice of external examiner is misjudged, by the way; it’s important to find someone with the right expertise and who will be broadly sympathetic to the subject and the approach taken. (You don’t want to spend two hours being grilled over a perfectly valid methodology which that examiner happens to dislike or even miscomprehend; that’s not what it should be about.)
Anyway, in the run up to my own viva in 2003, I found a certain amount of online material that helped me to understand better what was likely to take place, to focus on what I needed to do, and which made the process of preparation a good deal easier. There seems to be considerably more available now, so this list is really just a selection (google “phd viva guidance” for more). None of this relates specifically to history PhDs, but this experience is one that is much the same across disciplines.