The first volume of an autobiographical trilogy, Testament of Youth is Brittain's lauded reflection on that period of time. A great and lengthy work, it is not only a classic account of the Great War years but of feminist literature - it not only reflects on her own experiences but follows the impact of that war on a generation.
Or at least that's what the references to Testament of Youth that lead me to seek it out say. However I just couldn't get into it at all. I'm not sure if it was the style, the length, or just that I picked the wrong time to attempt it, but I skipped over much of the laudatory introduction and still couldn't make it to chapter 2 (entitled "Provincial Young-Ladyhood").
A taste, from pp. 27-28:
It would not, I think, be possible for any present-day girl of the same age to even imagine how abysmally ignorant, how romantically idealistic and how utterly unsophisticated my more sensitive comtemporaries and I were at this time. The naïveties of the diary which I began to write consistently soon after leaving school, and kept up until more than half-way through the War, must be read in order to be believed.Not so much interested, but I appreciate the offer. - Alex