What Five Works of Fiction Best Explain the 20th Century?

Name in the comments the five works of fiction that you believe best explain - not define or symbolize or exemplify, precisely - but in some way explain the past century to (in Brecht's phrase) 'those who come after. I have been asked this question by some high school students and before responding I thought I would consult the Wider Conspiracy. Particularly if the book is not something super well-known to an American audience, give a bit of description about when it was written, by whom, what it's about, and why it's on your list.

To give the full Brecht quote (from memory so might be slightly wrong and anyway a free translation), from the Three Elegies, written in Santa Monica and set to music by Hans Eisler:

"To those who come after, When man is no longer wolf to man, Remember us with forbearance."

Forbearance is a deeply under-appreciated moral virtue.