Everyone should read All Quiet on the Western Front by Erich Maria Remarque and Goodbye to All That by Robert Graves.

Le Feu by Henri Barbusse also comes highly recomended but I have yet to read it.

The First World War by Sir Martin Gilbert is a good general overview by an acknowledged authority.

The Great War - Perspectives on the First World War edited by Robery Crowley is a pretty good anthology of historical essays.

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...Old Europe, a once-dominant region now reduced to sucking at the geopolitical teat of America... they spent the better part of the last millennium conquering the world and taking the good stuff home with them... And what do they get for their troubles? Ungrateful colonies demanding their independence. And after you taught them how to play cricket!...

-Jon Stewart